Signs of a bad coolant sensor?

Mad Genie · Post by **Mad Genie** » Thu Jan 17, 2008 5:18 pm

Just pulled a log from my MS2 V2.2 and noticed wierd drops in my coolant temp reading (like inverted spikes, briefly dropping 10-15degrees creating what looks like big noise in the log). It appears to correspond to with acceleration or decel. Fine at idle and for the most port during cruise. Is this a sign the coolant temp sensor is packing it in. I'm going to order a new one but wanted to make sure I wasn't missing anything.

Was thinking along the lines of vibration is messing it up during accel or decel.

AR 67202 · Post by **AR 67202** » Fri Jan 18, 2008 3:24 am

could be air bubbles... this usually happens with cars that are running low on coolant, which is instantly cured by restoring the coolant level...

Minami Kotaro · Post by **Minami Kotaro** » Fri Jan 18, 2008 4:32 am

My CLT sensor has done that a couple of times. Both times it turned out to be because one of the wires got stripped and was grounding on nearby metal. Never could figure out why the throttle made the reading go up and down, though.

Mad Genie · Post by **Mad Genie** » Fri Jan 18, 2008 8:11 am

Thanks guys, I look into both those today....don't really want to pull the sensor if its still good as I'd have to drain most of the coolant.

Mad Genie · Post by **Mad Genie** » Mon Jan 21, 2008 3:02 pm

Well traced the wires back and they look good now grounding that I can find. Coolant level is good but still getting noise....only in the downward direction. Thats an increase in resistance right?

I've got a new sensor so I'll replace it in the next couple days and see if that does the trick.

Mad Genie · Post by **Mad Genie** » Thu Jan 24, 2008 2:17 pm

Must have been a bad ground or vref. I cleaned up my wiring and reran wires for the tps and clt. Signals are now clean as a whistle. Also ran a ground from pin 19 of JP1 on the relay board to the engine ground.