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.

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!
  1. Home
  2. Questions
  3. Check engine light on and got the codes P0700 and P0731

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Ignition switch going bad

Try another key to see if the problem is with the key; otherwise your ignition lock cylinder or ignition switch is bad. The ignition switch is the most likely cause of the failure you are having. I recommend having a...

Q: Check engine light on while driving after a drop in RPMs - 2003 Dodge Neon

Hi there - the best help going forward is to extract the problem codes turning on the Check Engine light. Most auto parts stores will read the problem codes for you for free. In a loss of power situation like...

Q: my trans malfunction warning light came on and 1st and second gear is slow. what can i do

When a module illuminates a warning light, generally there is a fault code that accompanies it. there can be many reasons for the concern like a low fluid level or a failing internal transmission component. Fluid leaks are common as...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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.