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Discussion Starter #1 (Edited)
Hi,

I'm getting fault code P0655 - Water temperature. ECU not receiving signal from the sensor.

Engine temp -30.4 C
Air temp -30.4 C

I'm assuming the thermistor has gone open on the coolant sensor but what worries me is why the air temp is also reading -30 :confused: Any ideas?

Thanks :thumbs:

EDIT: I've tested the coolant sensor in hot water and it's working ok. I've also checked the connector for voltage. 5v on the thermistor and 7.8v on the other?

Seems the air temp in the MAF and coolant sensor share the same earth through the ECU, checked continuity right through to the ECU and all OK so looks like dodgy ECU :(
 

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Hi Jake, in recent works I had the earth on the ECU mounting plate disconnected, it drove the car loopy, alarm was going off, all sorts! make sure it is good and solid on your car.
I assume you are seeing the -30 readings on MutiECUscan (or similar tool?) what is your engine coolant temp gauge in the dashboard telling you?
 

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I picked up a ECU kit (locks, immobiliser, sensor coil key, barell, ECU, ) on ebay for £50 recently. I bought it for diag purposes, and it all worked fine, so don't be daunted by the prospect of a new ECU it's not as complex as you might think.
 

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Discussion Starter #4
Hi Jake, in recent works I had the earth on the ECU mounting plate disconnected, it drove the car loopy, alarm was going off, all sorts! make sure it is good and solid on your car.
I assume you are seeing the -30 readings on MutiECUscan (or similar tool?) what is your engine coolant temp gauge in the dashboard telling you?
Yes it was MultiECUscan. After all the checking of wires etc in the end I gave up and was about to order a new ECU but after putting it all back together it's working ok :eek: So I am thinking it was just a bad connection :thumbs:
 
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