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Defective ECUs or other controller problems on your car?

tariktarik Posts: 344
Not that I have nothing else to do, but I have always been wondering about the following:

Did you ever have problems with one of the controllers (ECUs...) in your car, and if yes, which one?
Who (dealer/independent garage) diagnosed the problem and how?
Which make and model was it?
Did you have it replaced with a new one or repaired, and for how many $$$?

Let's hear your stories,



  • tariktarik Posts: 344
    This issue intrigues me because lots of components on a car can fail, but ECUs are rarely mentioned at all. They have to stand heat and cold, vibration and g-loads, engine degreasers and pressure washers as well as drag racing and stop-and-go for hours.

    Are those "black boxes" reliable enough as not to show up in any statistic?

    Atomic Tarik
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,457
    In all my years of messing with cars, I've never personally seen one that had to be replaced, except for flood damage.

    I've seen lots misdiagnosed as defective, but as I recall, only one acquaintence who had a genuine problem.

    ECUs are a lot like your refrigerator...a sealed unit that more or less just sits there and does it's job. No moving parts, usually well protected, and hard for a bad mechanic to get at and screw up.

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  • alcanalcan Posts: 2,550
    They can fail. Usually the first tip is a driveability concern (possibly intermittent) such as poor idle quality, poor throttle response, etc. Might light the MIL. Often accompanied by the infamous "No communication with ECU" message when a scan tool is connected to retrieve stored DTC's. Replaced one on a '93 Cavalier for a friend last weekend after performing the diagnostic routines as per the factory manual. Runs fine now. Incidentally, my parts supplier had this $230.00 (exchange reman) item in stock and the box wasn't dusty.
  • I had a bad one in my brother's '91 Olds 88 Royale 3.8L. It started just as alcan said, poor driveability, acted like it was overheating, check engine light would come on but the Tech 1 didn't find any codes, then finally wouldn't "talk" to the car anymore. Everything was normal at start up only after 20 minutes or so of driving would it start to act up, and the longer you drove it the worse it got. The speedo would go nuts or not work at all, since it gets it's info from the PCM, that was the final clue in the puzzle to just replace the computer. I got my replacement from the wrecking yard for $50, it was reman, in the box with a 2 year warranty.
  • alcanalcan Posts: 2,550
    Jg, with the currency conversion my price on the Cavalier ECM would be about $140 US. You got a h*** of a deal, especially with a 2 year warranty.
  • swschradswschrad Posts: 2,171
    an acquaintance used to carry a tube of SMT transistors that would replace those used in Ford series-II engine computers, as well as a 12-volt soldering iron and stuff. he ran into a lot of folks while RVing who had rigs that died cold on the road due to the output transistors in those RV chassis from Ford (late 80s-early 90s) conking out. the computers were averaging $250 each, and he made an incredible number of friends for life in the middle of nowhere by replacing the transistors for spark control in those units.
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