I am facing a weird issue with my 98 B5254T V70.
For quite some months it had regular cold starts struggles*, but nothing more.
But for the last few weeks, the car has been throwing a P0116 code. Reset it, it comes back in the next 10 to 30min of driving, cold or warm engine, doesnt seem to matter (done it almost a dozen times).
Looking at logs of the engine temp, every time the code pops up the reported temp jumps up a good 10°C all of sudden.
ECT is the green line, before the step it's at 64°C, after it's at 74°C.
Tested the sensor resistance, was within specs, swapped it for a used one i had laying around anyway. Not fixed
Replaced the ECU with another one because that was an easy job, no luck. While I was at it, checked that
- sensor resistance is the same if measured from sensor connector or ECU connector
- wires resistance between ECU plug and sensor plugs are basically 0
- gave the connectors a good clean with contact cleaner and sandpaper
I was about to replace the thermostat today, but cant find my spare one
Not convinced it would fix anything, but running out of ideas! Open to suggestions, especially ones that dont involve opening the whole engine loom
Not sure if that sudden jump is an actual change in coolant temp (thermostat opening/closing) or something in the sensor circuit going crazy. *car is running on E85, the cold start has been tuned and used to be perfect even at -10°C; but anything ever so slightly off (low fuel pressure, underfueling...) will make it struggle to cold start
