ECU test help please
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Joined: Apr 2023
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s500
ECU test help please
Guys I have been battling with this C230 forever, it has the no throttle response, engine just revvs, have had so much diag time and thrown parts at it. After tons of testing the mechanic came up with the ECU being bad, I sent the ECU to a place to module experts, they said the transistor was bad, did a whole replacement ECU for a bunch of money and said it would be plug and play, got the new ECU back, same thing, car starts and just revvs up and down with no throttle response, put it drives it clears for a second let me foot off the break it just bucks. Have had wiring harness tested, I need to know how to test the data coming from the ECU to the throttle, have tried multiple throttle bodys, new tps always the same problem, car only has 40K miles was garaged it’s hole life, 1 owner snowbird car.
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Joined: Oct 2009
Posts: 214
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From: East Idaho
2014 GL450, 2006 S500, 2003 ML350, 1996 C280 (Prev 1995 C220, 2002 CLK320, 1980 300SD Turbo)
How long is a long time and when did you acquire the vehicle?
If it's that old, with that low mileage and been sitting a long time the first place my head would go is the fuel system. Did you do a fuel pressure test and how many tanks of gas have you gone through so far? The ethanol can draw water from the tank if sitting long enough and this can mess up fuel injectors.
If it's that old, with that low mileage and been sitting a long time the first place my head would go is the fuel system. Did you do a fuel pressure test and how many tanks of gas have you gone through so far? The ethanol can draw water from the tank if sitting long enough and this can mess up fuel injectors.
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Joined: Feb 2026
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you can try reading the codes yourself with a scan tool like OBD2, it's usually pretty straightforward but requires some basic knowledge of ECU coding. The 2022 S class I have has a pretty user friendly interface for reading codes, but it's been a while since I've actually done it myself.
