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I have a problem with my car for about a year, related to the ECT sensor, which I always solved by clearing multiple DTCs (within this error, the fans work in failure, at maximum speed, even if it is 0 degrees outside). Today I decided to really solve this problem, changing the OEM sensor with an aftermarket one. I went from Bosch to Hella, with the same problem, which apparently came with the answer that the sensor was not to blame, but something else, random.

That error is random – sometimes it indicates high input, sometimes it indicates a sensor range error – and, from the multiple searches I did, I understood that it is a very common problem encountered by many people, with many underlying causes.

I drove around town for 5-10-15 minutes with a Delphi diagnostic and I found something strange: when such patterns happen, that random DTC is qualified, it is very rare but it happens over time.

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Does anyone have an idea what else I could check?

LATER EDIT PART I: NOT SOLVED

When I made this post, I have replaced just B24-I (Main sensor for engine coolant) and sprayed the connector with deoxidizer. I am not a mechanic or electrical engineer, I just understand basics let's say but followed the guidance proposed by MTA which was correct. ECU WIRING FOR ECT's Yesterday I was going deeper and purchased a trial license of Autodata for understanding wiring diagrams and also checked secondary sensor B24-II which was located in the coolant hose down near the radiator, changed loose connectors for each sensor in part. Problem not seen anymore after stress driving tests!

LATER EDIT PART II: NOT SOLVED

Apparently is another problem now and I think was a cumulated one if I have already solved the sporadic issue regarding vibrations... Now I can reproduce the issue 100% and it happens after each start-up power cycle of the car. I clear every time the DTC then in the first 5-10 seconds the temperature sensors go crazy and my guess is related to the alternator voltage stabilization somehow, I should keep temperature sensors under 13V. My feeling is related to voltage as I see another DTC's on headlights (short circuit all the time due to the guy which have installed the led bar in the headlamps from which I have bought the car...) the system go crazy for some tens of seconds but ECU stabilize it somehow and keeps working at 13V for the ECM sensors. I have seen at 14.5V is the trsshold limit when everything go crazy after testing also only with high rpm I hit 14.67V just accelerating and sensors go at -40... Should I mount some voltage stabilizers/regulators at 12.5V just for the ECM's?

VOLTAGE?

LATER EDIT PART III: SOLVED

Replaced by myself ECM (B24-I main coolant in engine) re-wire harness socket and hardening socket end with zip ties. After that problem solved (not occuring anymore after 500km of driving and 1 week of tests).

Thank you all for cooperation and support!

LXSoft
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1 Answers1

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You may have a bad connection or intermittent break in the wire somewhere between the ECT sensor and the ECM/PCM.

Suggest you refer to a wiring diagram and connect an ohmmeter with a tone output for continuity and start tracing each wire from the sensor all the way back to the ECM. At each plug, pull, push and generally manhandle the wires to see if you hear a break in continuity. For each span of wire between connectors, bend, twist and abuse the wire and listen for a break in tone. Also look/feel for abraded or melted insulation that is allowing a conductor to touch ground.

If you find a spot where the connection or continuity is inconsistent, either replace the plug, repair the crimp or splice a wire to bypass the break.

MTA
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