Would a bad temperature sensor cause this? - The Unofficial BMW M5 Messageboard (m5board.com)

rigsby · 7th August 2006, 15:28

Hi
My car doesnt run very smoothly, quite jerky/surgy this is very noticeable when cold and gets much better when warm, but still doesnt feel to be giving full power when warm. I've had new mafs, CPS and oxygen sensors. The only faults that have appeared in the past and never been addressed are implausible temperature readings. Do you think this could cause the poor running above? If so is it the sensor in the middle of the front of the engine I need to replace?? The temperature gauge in the instrument panel always is in the middle when warm.

Thanks.

bmw-lelle · 7th August 2006, 16:41

Well i have a fault-code 105. And i read "intake enginetemperature" faulty numbers. I have changed the watertemp-sensor u are talking about but it didnt help. If u find out what ur problem is maybe i will to

)

jclyman · 7th August 2006, 16:46

I don't know the answer to your question, but first I would guess that the temp sensor (the one for the temp gauge) is OK, as normal temp is from one needle width left of center to the center of the gauge ... in my car that is true of both the oil temp and water temp, even in the hottest weather. But, I would still be concerned about the codes you are receiving ... That said, have you considered spark plugs?

imolaman · 7th August 2006, 21:44

You could try changing the sensor. It is a cheap fix (about $20 I recall) and would take all of about 10 minutes to change, in DIY mode. Word of caution, make sure the engine is cooled down before attempting this, as hot coolant might scald you! Also, keep the new sensor close as you unscrew the old one. Once the old one is out, use your finger to keep the hole closed (to minimise coolant loss) and quickly screw the new one in place.

I was told by the dealership manager that the "implausible temp" could only be caused by either 1) a faulty thermostat or 2) the coolant temp sensor. In your case it sounds like the thermostat is fine (judging by your comment that the needle sits in the middle when the engine is warm, so it might be worth changing the temp sensor in this case.

Hope this helps.

Rudi

rigsby · 8th August 2006, 11:23

This is England so the sensor will no doubt cost $400,000!!!
But I will give it a go, thanks.
If not is there anything else that may cause the sysmptoms described? Its almost like the car doesnt want to react to the throttle properly...its quite sensitive, then suddenly it will fly, but then sometimes its just doesnt want to get going at all, its almost like a loose connection somewhere. Am I making any sense?