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Discussion Starter · #1 ·
I brought my car into my Honda dealer yesterday due to having 3-5 second hesitant starts and a low idle. They handed me a loaner car and told me they will call the next day.

I get a call today saying they could not replicate the hesitant start (I find that hard to miss since it does it every morning and after work) but they did notice a rough idle. They further looked into it and I was told the ECM had many corrupt errors and it needs to be replaced.

Has anyone ran into any issue with a bad ECM before? I understand that the ECM is the computer but what exactly does this control?
 

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I brought my car into my Honda dealer yesterday due to having 3-5 second hesitant starts and a low idle. They handed me a loaner car and told me they will call the next day.

I get a call today saying they could not replicate the hesitant start (I find that hard to miss since it does it every morning and after work) but they did notice a rough idle. They further looked into it and I was told the ECM had many corrupt errors and it needs to be replaced.

Has anyone ran into any issue with a bad ECM before? I understand that the ECM is the computer but what exactly does this control?
ECM is the Engine Control Module.... Pretty much the brains of the engine, it controls Spark, Fuel Injection Timing, fuel cutoff, diagnostics, etc.. Shifting (automatic transmission), cruise etc...

Having some insight into this, I can say the modules on newer cars should do a quick selftest when the car is first started. If the module fails due to memory corruption, it would not allow the car to start as a safety measure. (Also keeps Honda from getting their a** sued off, if the engine where to go crazy and run you off of a bridge). At a minimum a CEL should be thrown...

If neither is happening, I would question if the ECU is the problem...
 

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Discussion Starter · #3 ·
Thanks for your insight. When the Honda Service Rep called he called it an Electronic Control Module. You are calling it an Engine Control Module. Do you think he meant the ECU instead and just mixed it up?
 

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Thanks for your insight. When the Honda Service Rep called he called it an Electronic Control Module. You are calling it an Engine Control Module. Do you think he meant the ECU instead and just mixed it up?
Don't know... It is possible he could have meant a different module, I have seen techs (and some engineers) frequently misuse the terms...
 

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Discussion Starter · #6 ·
ECM, PCM, ECU, all the same thing.

It controls all engine functions, tach functions, and HVAC functions.
Thanks for clearing this up! I hope this will fix my starting and idle issues. I have been dealing with too many battery replacements because it was getting misdiagnosed.
 
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