10 Symptoms of a Bad Fuel Injector (and Cleaning/Replacement Cost)
Most vehicles from the 1980’s and newer are equipped with advanced electronic fuel injection engines (replacing the carburetor). A major part of this system is the fuel injector.
While you may never have a problem with your fuel injectors, sometimes they get dirty, clogged, or completely fail and need to be replaced.
Below are the most common symptoms of a bad fuel injector and the average cost to replace them (when cracked) or clean them (when clogged).
Common Bad Fuel Injector Symptoms
Here are some of the most common signs of a fuel injector issue. Keep in mind that the fuel injector in question may simply be clogged so don’t automatically think that replacement is necessary.
Using a bottle of fuel injector cleaner may help, and even better, doing a proper cleaning with a fuel injector cleaning kit is recommended before spending the money on new injectors.
#1 – Rough Idle or Engine Stalls
Because your vehicle is not getting enough fuel or an uneven supply of fuel, the RPM while idling drops below the optimal level and results in a rough or even violent idle. If the RPM falls too low, the car may actually stall and you will need to restart.
This issue is particularly noticeable when your engine is cold or when you’re sitting at a stoplight.
#2 – Engine Vibrates
Bad fuel injectors can prevent specific cylinders from firing properly, resulting in noticeable engine vibrations. As you drive, you may feel a rhythmic shaking (through the seat or steering wheel) or hiccupping sensation, especially when maintaining a steady speed.
This happens because the affected cylinder isn’t receiving the correct amount of fuel, disrupting the engine’s normal firing sequence.
The vibration can vary in intensity depending on which injector is malfunctioning and how severely it’s affected. You might also notice the vibration is more pronounced at certain RPM ranges.
#3 – Engine Misfires
Engine misfires happen when a cylinder doesn’t fire correctly, often due to a clogged or malfunctioning fuel injector. You’ll likely notice a hesitation or stumble when accelerating, almost as if the engine is briefly losing power. In some cases, you might feel a slight jerk or shudder.
While fuel injectors aren’t the only cause of misfires, they’re a common culprit and should be one of the first things checked when this symptom occurs. Any time an engine’s air/fuel ratio is upset, you’ll want to resolve it quickly.
#4 – Check Engine Light Turns On
The most obvious sign of any car problem is when the “Check Engine” light illuminates on your dashboard. Although this could mean a lot of things, a bad fuel injector (indicated by a code such as P0201, P0202, P0203, or P0204) could be one of them.
Any time an injector delivers less fuel than needed (or more in some cases), the engines efficiency is lowered and can trigger the CEL to come on. Use an OBD2 scanner to confirm the issue.
#5 – Fuel Leak
If your fuel injector is actually broken or cracked from damage or old age, then fuel will begin to leak out of it. You may notice wetness around the fuel rail area, and in severe cases, actual gasoline pooling on the ground underneath.
In most cases, the leak originates from a deteriorated fuel injector seal. But no matter the severity of the leak, you’re dealing with fuel, making it a significant fire hazard. Get it fixed ASAP.
Read Also: How To Get Rid of Old Gasoline
#6 – Fuel Odor
This goes along with a fuel leak but when you have gasoline that’s not getting burned due to a damaged injector or one that’s stuck open, you’re going to smell gasoline. Sometimes the issue may be your fuel lines or a faulty sensor telling the ECU to inject more fuel than in necessary.
Either way, you need to find the cause of the fuel odor and fix it right away before it becomes a major fire hazard.
#7 – Engine Surge
If the fuel injector is spraying too much fuel into the engine cylinder, this will create a surge in the engine. You might feel the car speeding up and slowing down slightly while maintaining a steady throttle position. This uneven performance is particularly noticeable during highway driving.
Engine surging can also present itself as RPM fluctuations under constant load, rather than remaining at a constant RPM.
#8 – Bad Fuel Economy
Similar to how a bad fuel injector may not deliver enough fuel, it may be delivering more fuel than necessary. One of the most obvious signs of this is having to fill up your gas tank more often than usual.
Your car’s computer might try to compensate for perceived fuel shortages by injecting even more fuel, further worsening the situation. This excess fuel consumption not only hits your wallet at the pump but it’s not exactly good for the environment.
#9 – Failed Emissions Test
And speaking of the environment, because a faulty fuel injector can cause an uneven or incomplete fuel burn, increased emissions are a result. This means your chances of failing an emissions inspection increase greatly. If you’re also getting a Check Engine light, failure is guaranteed.
In some cases, a fuel injector leak can cause the air/fuel mixture to be so rich that it eventually burns out the catalytic converter.
#10 – Uneven Cylinder Temperatures
If you have access to an infrared thermometer (Klein Tools makes a decent, cheap one), you can use it to measure temps across your exhaust manifold. Each cylinder should have a similar temperature when your engine is running properly.
If you notice signification temperature variations between cylinders, you may be dealing with uneven fuel distribution, with a fuel injector being a possible cause. Poor engine performance often comes along with it. That said, you’ll want to take a look at your spark plugs as well.
How a Fuel Injector Works
The basic function of a fuel injector is to supply the engine with fuel. The injector sprays (injects) fuel into the cylinder of the engine through a nozzle so that the internal combustion process can begin.
The fuel must be delivered at the right time, in the right amount, and at the correct pressure, angle, and spray pattern.
The Engine Control Unit (ECU) is the central computer or “brain” of any vehicle and manages many individual components, such as the fuel injector. Via various sensors, the ECU makes sure the injector sprays fuel at the right time and in the right amount so the correct air/fuel mixture is created.
A vehicle’s fuel pump pushes gasoline from the tank, through fuel lines, and into the fuel injectors. When the ECU determines fuel is needed, it communicates this to the fuel injector solenoid which then opens to allow the pressurized fuel to spray into the cylinder.
See Also: Common Low Fuel Pressure Symptoms
Cleaning Cost
Fuel injectors do not last forever but you can take steps in preserving their lifespan for as long as possible. Many experts recommend that the fuel injectors be cleaned every 30,000 miles or so. That way, the injectors don’t get clogged and prevent fuel from spraying into the cylinder.
Fuel Injector Cleaner
Using a bottle of fuel injector cleaner every now is good preventive maintenance and it’s fairly cheap. Expect to pay about $10-$15 for a bottle of cleaner.
For maintenance, you’d use one bottle right around the time you do a regular oil change but as often as every time you fill your gas tank if the injectors are already showing signs of being clogged.
Related: How to Clean Fuel Injectors
Professional Fuel Injector Cleaning
For more severe cases of dirty or clogged injectors, a more expensive professional cleaning is required. Expect to pay anywhere from $50-$100 for this service.
Some companies even allow you to ship them your dirty injectors where they’ll clean them for around $15-$20 each and then ship them back. They’ll probably do the most thorough job but you’ll obviously have some down time if you need your vehicle.
DIY Fuel Injector Cleaning Kit
Alternatively, part-time or full-time professional mechanics can purchase a fuel injector cleaning kit that will usually pay for itself after a few uses. A good kit (like this OTC set) will include various adapters to allow you to work on most fuel injected vehicles.
Fuel Injector Replacement Cost
Best places to order parts? See: 19 Best Online Auto Parts Stores
Fortunately, most fuel injector issues can be fixed with a professional cleaning or replacement of the O-rings if a leak exists there. But when a fuel injector cracks or breaks, replacement is necessary and it can be expensive.
Although fuel injectors are individual, they are designed to work as part of a team with the other injectors. So if you’re wondering if you can replace just one injector or all, the answer is almost always to replace them ALL.
Depending on your make and model, you can usually expect to pay around $800 to $1,450 for a complete fuel injector replacement. Parts alone are about $600 to $1200 and the labor cost will run about $200 to $250.
There are exceptions of course. Using non-OEM parts can save you some money while certain makes/models of vehicles can run upwards of $2,000 for a replacement. It makes sense to shop around for this type of job.
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I put SeaFoam in my 2016 BMW 550 when I filled my tank 2 days ago. I did accelerate fairly hard getting on to the interstate and a “Drivetrain Malfunction” warning came up and my car started running like hell. Violent shaking, etc. I parked it at a nearby grocery store and I guess I am going to get it towed if necessary (I hate it because tow truck drivers always treat cars like hell). Is it possibly a clogged fuel injector?
I have no idea. Did you follow the instructions on the Sea Foam can? Were there any problems with the vehicle before adding Sea Foam?
Codes PO171
PO174
CO300
PO301
PO430
Rough idle and when going up a hill and accelerating lost all power to where the gas pedal can be to the floor and will only go 20-30mph. Stuck in this mode any ideas?
What is the year, make, and model? Sounds like your vehicle is running lean. There could be an air leak behind the MAF sensor, for instance. You could try a smoke test to check for air leaks.
My Corsa lite 1.3s put over fueling but rev 500 and cutout engine as driving,all sensors changed but still nothing changed
I don’t understand. Are you saying you overfilled the gas tank?
1998 Opel Astra
can someone help me with this issue, I bought a beautiful 2005 ford mustang but this cas keeps shooting gas from the fuel injectors 7 mechanics have changed all O rings changed the fuel rails twice, guy asked me did i smoke i said no and sold me the car for all my savings a the time 5k
Hi,
My mini cooper D suddenly slowly rolled to a stop as I was driving and wouldn’t turn back on. RAC came and said there was an error with fuel injector 1. Towed to a garage and the next day they went to work on the car and it was starting fine! They have checked it multiple times but seems there is no longer an issue. I hadn’t driven it for about a week before it broke down and the temperature had been around -3°C for over a week. Could it have been that the cold weather temporarily affected it? Should I still get the fuel injector replaced just in case?
I have a hard time believing that a single bad fuel injector would cause the vehicle to stall while moving and not turn back on. If it were my car, I would clean or replace that fuel injector and then do some diagnostic work to see if there is another problem elsewhere.
I have 2010 Ford Escape ( bought used 3 weeks ago) oil light immediately came on, dealer “fixed” claiming faulty sensor, 1 week later on again and a dripping noise, also notice fuel economy worse. Went to dealer and different garage said sensor had not been replaced and this was the problem. 1 week later engine light flashing, garage says fuel ignition issue. Could these be related?
I don’t know. I wouldn’t think they’re related.
There’s almost always a bunch of maintenance you need to do when you buy a used vehicle. The better the original condition, the less repair work you will have to do. Sounds like this Escape may have been neglected a bit.
Hi, sir, I have Toyota Aqua 2012 my car engine rattling at the speed between 20 to 35 when it shift from EV mode to engine, L have done the following work at but no improvement gain
1. clean spark plug, fuel injectors, ignition system and throttle body.
2. clean fuel pump, air filter
i am very depressed plz advise what to do further in this regard
Is there a lot of movement in the engine? I wonder if you could have a bad motor mount? You would probably feel a “clunk” as the engine shifts when hitting the gas, taking your foot off the gas pedal, or when the car switches from EV to combustion engine mode.
I might also listen to your starter in case starting the engine is making a weird noise.
I Have A 1998 Honda Civic EX. I Have A Loss Of Power Issue When Driving After 60MPH, When I Am At The Same Speed For About 15 minutes My Car Will Lose Fuel Power For About 10 seconds then kick back in Then Do It Again. This Is Repeated About 4 Times Then It no longer happens unless I up my speed more. I’m Currently Trying to determine if this could possibly be caused by the Fuel Injectors being faulty. I’ve Replaced My O2 Sensor B2 , New Catalytic Converter, New Distributer, New Fuel Pump, New Spark Plugs, New Air Filter, New Fuel Filter. I Am A Loss And I Have No Other Possibilities That Come To Mind Besides A Possible Dirty MAF Sensor. I’d appreciate any help if it could be given ☹️
Sounds like your issue might be fuel starvation. Check to make sure your gas gauge is working and see if you can determine if the gauge is accurate.
I have Nissan Sunny 2015. recently i change spark plug and one coil. but still my car consuming more fuel.. I am getting mileage only 10 kmpl.. car is not showing in engine light or tyres pressure then why i am not getting good mileage..
There are so many factors that may affect fuel economy. Here are some ideas to get you started.
Check your engine air filter. Replace the filter if it’s dirty. Depending on how many miles are on the vehicle, you may want to replace the fuel filter as well. Typically if you have over 100,000 miles on the vehicle and it’s never been replaced, you should think about replacing the fuel filter.
Check your tire pressures. Low tire pressure will consume more fuel.
Hi. I added these fuel cleaners to my 2013 Subaru Impreza, and it’s been a hell. I’m experiencing this engine stalling recently with the check engine lights. I’ve used my OBD scanner which shows a P0171 code “fuel too lean?”. Please any advice I can get?
What problems were you experiencing before you added fuel cleaners? Which fuel cleaners did you add, and how much?
My Corolla 2009 was running great. After having gas treatment in my gas tank the same day my car started acting up. I had this car since new and I had never add any treatment to the gas tank before.
We ended up replacing the engine. 🙁
What type of “gas treatment” did you use?
My Dodge Ram 1500 starts misfiring and then stalls completely, there is a strong fuel odor in the engine compartment, engine cranks but does not start, after a time maybe an hour later I have to depress the gas pedal constantly to start the engine, is there any advice about this situation Thanks
Check for fuel leaks if there is a strong fuel odor. If there is a fuel leak that is bad enough to substantially drop fuel pressure, that could cause issues starting the vehicle.
An injection pump delivers diesel fuel to the engine cylinders on a predetermined schedule. It operates such that fuel is injected at a very precise point in the engine cycle. It is also common for the pump belt on gasoline engines to be driven directly from the camshaft.
Injector systems can take different forms. Pump-line-nozzle, unit injectors and common rails are three varieties – modern e-injectors reach very high injection pressures.
Bad Fuel Injector Symptoms includes
Here are a few signs there might be something wrong with your fuel injectors.
The Engine Misfires. Dirty fuel injectors may cause your vehicle’s engine to misfire.
Idling Gets Rough.
Your Gas Mileage Tanks.
The RPM Needle Starts to Dance.
Your Car Won’t Start.
Hi. I have some issues with my 2004 diesel Mondeo. There appears those codes on diagnose: 0251, 1203, 1211, 1246, 1632, 1664. And symptoms are lose of power on ramps but not on normal way, really smoking with hihg rpm. Are injectors have really big problem or they just need to ve cleaned?
hi I have a Mercedes a class I’ve had all 4 injectors replaced an its running like one has gone again I’ve took in in garage they say number 1 injector has gone I’ve ordered them to replace this one if it still runs like a rattle snake what could this be now
Interesting. I wonder if there is a problem further up the fuel system that could be clogging the rail before the injector itself. I am not familiar with the A Class, so this is just a guess.
What led them to believe it is an injector and not a coil or spark plug on that cylinder?
Hi my Vauxhall antara 2.2cdti blowing smoke revs stuck at 3 k done full service aswel dpf , fault code sayin 1 & 3 injectors any advice before I pay £600 for 2 injectors
Those are some expensive injectors. You could try having them tested to see if they are the problem, or if it could be something else like the electrical connectors that power the injectors.
Hello. Codes: P0304 – P0101 – P0068 – P0020 – P0021 – P0174 – P0157 – P2000 – 2100 – P0800 – P0A47 – P0325. Diagnosis eliminated anything to do with the ignition system. Mechanic went on to check fuel injectors and reports C-4 injector only getting 4 PSI and the injector head is not moving. Recommends replacing all bank 2 injectors. States this will clear all codes except for camshaft solenoid, which will also need replacing. Does this sound reasonable?
Wow, that’s a lot of seemingly unrelated codes. Have you eliminated the timing and electrical issues as possible causes?
Since the ecu is the brain, can’t it say which injector is the culprit?
Sometimes, but this would often manifest as a “Cylinder X Misfire” or “System too Rich/Lean” codes. The ECU tells the injector how long to stay open (injector pulse width) but would have to rely on other sensors to help you detect a bad injector, such as a knock sensor or O2 sensor.
i saw engine ligths but i thinking about fuel injectors.please advise
What codes were stored with that check engine light? What made you consider the fuel injectors?
I ve got a problem my Ford Ranger 2.2 diesel angine is not performing,theres no power at all,ts is smoking it end at 80kms speed.Im at Pongola,where is the nearest service of injectors i think the need a service.Pls give the coatation if service all four.
It’ll probably be a few hundred bucks to replace all of them.
Hyundai Sonata has no power. Already replaced spark plugs but didn’t help. Bad oil leak as well!!!
What led you to change the spark plugs? Any other symptoms you are experiencing? What tests or diagnostics have you tried?
I use a Toyota haice power van with D4D engine turbo charger is not working could it be the result of engine malfunction when it exceed 80 kmp or injector problems
Hard to say. I recommend you bring it to a local mechanic so he can help you diagnose the problem.
How could a ignition give u a leaky fuel problem as stated above?
The ignition system doesn’t cause fuel issues. If you’re referencing Claude Desaulniers’s comment, he was mentioning that the symptoms in this article could also be caused by a faulty ignition system. In other words, just because you have an engine misfire doesn’t mean the fuel system is the cause.
So I have a 2004 Ford F250 7.3 L. I have every single symptom named as far as it being bad fuel injectors. I just bought the truck a couple months ago and the previous owner already replaced to injectors. Now it is definitely showing me that there is more. But I am having another issue that I am uncertain up. I will be driving down the road in my entire panel will completely turn off no power. Is there any correlation with this? I know it does not seem like there is but am I missing something here in the diagnosis?
Are you sure the battery and alternator are good?
I got an 04 Chevy and my gauges cutoff but the truck stayed running
I turn off the ax and it fixed it but then started getting choppy
Did you find out anything on yours that might help me pinpoint my problem
Many of the above symptoms can also be caused by a bad spark plug or a bad spark plug coil.
Yup, pretty much any of these symptoms except the fuel leak could also be caused by the ignition system.
You missed an important symptom, the fuel injector plunger is leaking fuel into the cylinder and causing gas to accumulate in the oil and often it will foul the plug causing a misfire. A misfire code can actually be caused leaking fuel onto the plug fouling it. It seems like once a plug is fouled in this way, it never fires as well as it should and it should be replaced with a new plug. Some motors, like the Dodge 4.7L V8 are very susceptible to this.
That is a great point. A leaky fuel injector could certainly foul a spark plug. However, I would call that a cause, not a symptom. The “symptom” you would experience could be a misfire, worse fuel economy, or fuel odor from constantly running that cylinder rich. Thanks for bringing that up.
what about failed emissions test? how is that a symptom? do you experience the emissions going up? you must have a real bond with mother nature
Yes it could. If the injector is leaking fuel into the combustion chamber when it’s supposed to be closed, you can foul your O2 sensors and reduce the life or efficiency of your catalytic converter. You might fail the sniffer test too.
Please advise my car is very sluggish going up a hill and the rpm goes and down without me pressing . And when you start the car in the morning the engine shakes. And there is a misfire. Not sure if it is the fuel injectors. Please advise
It could be a number of things, unfortunately. See if you have any check engine lights that give you a clue as to what’s going on. Next, I would start by checking the spark plugs, as they are usually cheap and easy to replace. Next, check for vacuum leaks by performing a smoke test.
please advise if you got help and what you did my car doing same story please
2013 Hyundai Elantra have issue with gas in oil also loud klick noise on idle believe injectors 1 or more are cracked or bad oring what say you
The first thing I would try is put the end of a screwdriver on each injector, with your ear on the other. Listen for changes in the sound between injectors, see if this gives you any clues as to what’s going on. If they’re firing, you should hear a little click periodically. If one click is louder than the rest, I’d start investigating what could be the cause on that cylinder.
You could pull the injectors and check or replace the o-rings. If you’re not comfortable doing these things, bring your car by a trusted mechanic for a diagnosis. Gas in the oil is probably more than just an injector o-ring.
Gas in oil? Sounds like worn valve guide seals
Hi there my car has got diesel smoke , some says injectors so now I’m not sure and no power on up hill any help please
Can agree with all given above except no check engine light.
Sometimes when you add fuel cleaners they loosen particles/sediments in fuel lines and fuel rails causing clogs in injector screens, injector tip spray valves, needle valves in carburetors, and can clog filters. Usally this occurs in older vehicles. It’s happened to me before also in the past. I just drained all my fuel from tank, flushed out fuel lines and fuel rail and replaced my injectors. Cheapest for me but l did it myself. Change fuel filters and go from there. Those cleaners can also be a nightmare.
Excellent point.
hi I have a 2012 s-max titanium I have four codes that is stored they are p0093,p0094,p0096 and p1168 the first 2 codes I think are fuel leaks p0096 intake air temperature sensor 2 circuit bank 1 and p1168 is fuel range sensor in range low failure I’ve changed the fuel filter so far the car starts and have no problem when driving but engine malfunction comes on when speed is 60+ mph what would be the next steps any info would be great.
My car is sending to much fuel so it is causing the the car to overflow and drops the rpm needle and after it idles hush when u accelerate after leaving the accelerate paddle it switches off
This is a best write up I have seen on the topic.
After using a gas treatment in my tank. I am having trouble getting my engine to fire. It cranks but if I pump my gas peddle it fires never did this before, ever. Help!
same never again!!!! smh
Mine was dirty I used gas treatment it made it worse and I had to replace the whole fuel injector