Skip the auto shop - Our mechanics make house calls

Q: Check engine light on and got the codes P0700 and P0731

asked by on

My check engine light came on two nights ago and I went to O'Reilly auto parts to have them give me a diagnostic test. There were two codes that showed P0700, P0731. Please help and explain what this means and possibly what the price may be.

My car has 55100 miles.
My car's transmission is unknown to me.

A: Diagnostic trouble code P0700 and code P073...

Diagnostic trouble code P0700 and code P0731 indicates that there is a fault in your car's "automatic transmission control system". Although there could be a faulty "part," (such as a shift solenoid or speed sensor), there are some preliminary checks that you can perform just in case it is resolvable (or at least, "diagnosable") without the assistance of a mechanic.

For example, on Neon's, there are reports of the heat exchanger in the radiator (the heat exchanger cools circulating transmission fluid) leaking and then letting the engine coolant mix with transmission fluid.

So you want to check and be sure that the transmission fluid is not "contaminated" with coolant because that sort of contamination could "potentially" cause these codes to set. It is also possible for a low (or even too high) transmission fluid level to cause hydraulic malfunctions that in turn will set the codes you are seeing.

So those are two things you can check right away. If those initial checks of fluid quantity and quality do not reveal anything, then you should have an expert evaluate the following mechanical and electrical components in the transmission: the transmission control module, transmission valve body, shift solenoids (typically in valve body); and a check for a possible open or short in the wiring TCM wiring harness. Typically, the problem will be found within the foregoing components without having to remove the transmission. But if not, there is an internal mechanical problem that will require further evaluation. If you would like to get a precise diagnosis, a certified professional from YourMechanic can come to your car's location to inspect the Check Engine Light and follow through with the necessary repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Car hesitation and misfires

Hello. The most common cause of this is a tune up issue. If the spark plugs are worn then this can happen. If the check engine light is coming on I would typically start by scanning the computer for codes....

Q: Dodge Neon SE

If the fuel pressure drops after you shut off the engine, then you may have a bad fuel pressure regulator, or a bad fuel pump. Have the fuel system diagnosed by a mechanic; a diagnosis of the start up...

Q: Clutch bad in vehicle

Hello. From the symptoms you provided, it appears that your clutch is worn-out, or the friction material has come off the clutch disc. This is a major job that requires a qualified technician who does heavy duty work to replace...

Related articles

How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.