P0135 Code (O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1)


Oxygen sensors are able to function properly because of certain heating components that are built into them. A heater circuit is what drives these elements to produce the necessary heat. If there is a short in the heater circuit or if it faces tough resistance, then it could cause the running engine to be rough. This will result in a reduced fuel economy and an uncomfortable driving experience.

What Does Code P0135 Mean?

When you notice a situation of your engine running rough, the first thing you should do is use a diagnostic scanning device on your powertrain control module.

If the scanner generates code P0135, then it means there is a malfunction in the heater circuit of sensor number one, bank number one.

The bank number one is in reference to the side of the engine where cylinder number one is located. This is the location where the oxygen sensor heater circuit is not working correctly.

The powertrain control module normally puts the oxygen sensor heater circuit through a test every time the engine is started. The test checks to see if there is an open circuit, too much current being drawn, or a short in the circuit.

Also, the module watches to see the length of time it takes for the oxygen sensor to heat up. If it takes a long time for it to heat up or if any of those other three problems are detected, then the module will generate trouble code P0135.

How to Fix Code P0135

It may just be that your heated oxygen sensor is faulty and needs to be replaced. It may have blown a circuit fuse or just has a bad electrical connection.

In rare cases, your powertrain control module might not be working correctly. But you are never going to know unless you have a certified auto technician look over your module and heated oxygen sensor. They will be able to tell which is at fault and which is not.

It is easy to wait too long before you do something about this problem. The two most notable symptoms will be a bad fuel economy and the “Check Engine” warning light coming on. Those are not really symptoms that are going to prevent you from driving anytime soon.

But if the problem continues to persist, it could potentially cause an emission problem and maybe something worse for your engine. Do not take anything to chance. As soon as that warning light comes on, take your vehicle to a professional.


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