P0730 Code (Symptoms, Causes, and How to Fix)

When you’re driving down the road you don’t want to see the check engine light turn on. But with a code P0730 you’ll have exactly that happen, and you’ll likely have some performance problems cropping up too.

But what does a code P0730 mean, how serious is it, and how do you get it to go away? We’ll answer all those questions and more for you here to help get your vehicle back on the road in no time.

P0730 code

What Does Code P0730 Mean?

OBD-II Trouble Code P0730 Description
Incorrect Gear Ratio

When you read a trouble code and see “incorrect gear ratio” it can be a little panic-inducing. What exactly is a gear ratio and more importantly, why is it incorrect?

The gear ratio a code P0730 refers to is an automatic transmission with a different input RPM sensor and transmission output RPM sensor than the ECM expects.

It sounds like a more complicated problem, and in many ways it is, but the short answer is that the transmission isn’t producing the right amount of power for the wheels to use!

Symptoms of Code P0730

car starts then dies

If you have a code P0730 you’re likely to notice a few more symptoms than just a check engine light. While it’s technically possible to have a code P0730 without any additional symptoms, it’s an extremely rare occurrence.

Common problems accompanying a code P0730 include a vehicle that isn’t shifting properly and a decrease in fuel efficiency. You might notice problems only with specific gears or at certain speeds, or you might notice problems across the board.

And while you’re likely to have a drop in fuel efficiency, unless you’re actively monitoring how much fuel your vehicle is using you might not notice the drop.

Finally, while it’s less likely than shifting problems or drops in fuel efficiency, it’s also possible to notice a myriad of performance problems with a code P0730. These problems can range from a vehicle dying completely to misfire-like sounds and symptoms.

  • The vehicle will not shift properly
  • Decrease in fuel efficiency
  • Performance problems

Causes of Code P0730

symptoms of bad transmission valve body

A code P0730 means there’s an incorrect gear ratio coming from your transmission, and a problem like that sounds like it might need a lot of computer repairs at first blush. However, typically that couldn’t be further from the truth.

Two of the most common causes of a code P0730 are defective shift solenoids or a defective valve body. If these components start to fail it creates a mismatch between the desired and actual output, throwing the code P0730.

Another potential cause of the code is a defective engine coolant temperature sensor. While this might not make sense at first, the more you think about it, the more it makes sense. The engine coolant temperature sensor opens and closes as the engine reaches certain temperatures.

This allows the engine to control the overall temperature which is what the ECM uses to fine-tune engine performance. If the sensor starts to fail, the ECM will still think it’s going to work a certain way when it isn’t. The engine won’t be able to fine-tune performance as easily and it can throw off the gear ratios a bit.

Finally, when was the last time you changed the transmission fluid? If it’s been a long time, it’s not going to work as it should. Old or dirty transmission fluid will require more work for the transmission to achieve the same level of performance, and it might not be able to perform the way it should.

If this is the case, flushing the transmission fluid might be all you need to clear the code and get your vehicle back in working order!

  • Defective shift solenoids
  • Defective valve body
  • Defective engine coolant temperature sensor
  • Dirty/old transmission fluid

Is Code P0730 Serious?

Yes. While the cause of a code P0730 can vary quite a bit, one thing that doesn’t change is that it affects the overall performance of your vehicle. You might end up stuck in a lower gear, or your vehicle might try to skip a gear completely.

When you’re driving down the road, this translates to a vehicle that isn’t responding the way you expect it to. You might experience a loss of power, or you might experience a sudden surge in power you’re not expecting. Either way, it can lead to big problems!

You also risk further damaging components in your vehicle since they’re not working the way they should. Finally, since it’s possible that your vehicle will stop running while you’re driving, this can create major issues on the roadway.

Complicating matters further is that you might experience these problems at different speeds and different gears, so there’s really no way to know what’s going to happen or what to expect. Because of this, you should not drive your vehicle if it has a code P0730.

How to Fix

signs of low transmission fluid

If you have a code P0730, you want to know how to get it to go away. Troubleshooting a code P0730 all starts with figuring out what’s going on under the hood, and to do this you really need an automotive scan tool to tell you the different sensor readings.

This will allow you to monitor and activate different sensors at different times to see what is and isn’t working the way it should. While you might be able to make an extremely educated guess about what’s going on without an automotive scan tool, in the end, you’re just guessing and hoping you’re replacing the right part.

However, one thing you can do without a scan tool is check the transmission fluid. Pull out the dipstick and check the color. If it’s bright red, it’s still in good condition. But if the transmission fluid is a very dark brown or black, it’s time to change it.

Adam Mann


  1. 99 Chevrolet K3500 : I’m getting code PO730, along with a CO238 code. Transmission is newly rebuilt and it’s not shifting correctly. Have replaced all wheel sensors and speed sensors but still having this problem. Please help!!!!

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