Code P0601

[Bruce]

My Chrysler 2000 Grand Voyager minivan always gave me an engine light because I was using an aftermarket gas cap. Finally, I failed inspection because of this (Code P0601). So I purchased an new gas cap that fits well, but the warning light isn’t going out.

Is there an easy fix/diagnosis for this? I’ve read it’s either low voltage to the ECM; or I need a new ECM altogether.

Thanks.

Topic

[Billy]

P0601 has nothing to do with the gas cap. Typically it’s a bad PCM, though checking for low supply voltage to the PCM wouldn’t hurt.

[Richard Kirshy]

Agree .
P0601 diagnostic trouble code is set when a memory check sum error is detected with the internal control module. This is a error internal to the ECU and is found when the ECU performs self-checks. P0601 then causes the Check Engine Light to illuminate and failsafe mode to become enabled until normal operation resumes or the code is repaired.

Common causes:
ECU failing or has failed.
Low voltage to the ECU.

Diagnosing the issue:
A visual inspection will be performed to look for any damaged wiring or circuits.

Then, a multi-meter will be used to check for proper voltage supply going to the ECU.

Lastly, the ECU will need to be tested. Each vehicle has its own testing procedures for the ECU.

[Bruce]

After code checks at 2 AutoZones and 1 Pep Boys, I got a mechanic to hook the ECU up to an actual computer to look at and reset the ECU. He told me the ECU is not communicating, and confirmed what the auto stores told me that there was nothing wrong with the car… just an “Internal Control Module Memory Check Sum Error – PCM RAM Memory Failure.” So I do need a new ECM. He also told me a good used one should cost $50. All I’m finding on the internets are units selling for $150. Is there a reliable source for these ECUs that will sell them for a reasonable price? RockAuto doesn’t sell them.

[Dave Tidman]

Remember getting the ECU is only step 1. The ECM needs to be properly flashed in order to work in your vehicle.
I would still check the voltage going to the ECU. If it is low, it can cause a number of issues inside the ECU.

[Bruce]

After weeks of investigation, I had a local mechanic work on and replace my ECM. I was told to drive it for 40 miles to set up the data or something. 8 miles out, the engine light comes back on. The mechanic asks if my gauges are bouncing around and acting crazy. Apparently the new code is instrument gauge failure. What fresh hell is this now?

[Author]

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