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Engine warning light (EOBD)

3K views 3 replies 3 participants last post by  chriskath 
#1 ·
Hi again

2nd post in the hour... but this is what sundays are for :)

I have been trawling the forum for an answer but I hope someone can think about this with a fresh brain!

The EOBD stays on after the starting the engine around 30% of the time. Sometimes it will be off for a whole week. If it does come on it can sometimes be fixed by restarting the engine a few times.

Also, when it comes on the fan will run constantly. I do not know if this is the ECU just being cautious or it is a temperature sensor fault.

Regarding the temperature guage - it normally sits just off the bottom, around the 50 mark... I seemed to remember it getting near 60 once! But the heater seems toasty enough.

I am reluctant to take it to a garage if it is an intermittent wiring fault as this will probably cost a fortune in labour.

If someone can give me a list of things to check I would appreciate it. I do not have any sort of workshop manual to help me test the temperature sensor for example.

I don't know if it is running rich.. it only does 25mpg - but most of this is my wife going 1 mile to work in the winter months. She cycles when the weather is better!

Thanks!
 
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#3 ·
Re: Engine warning light (EOBD) (temperature sender / thermostat)

I have managed to deduce the following that may be useful to others:

The fan comes on when there is no signal coming from the temperature sender unit - obviously to protect the engine. This can be demonstrated by unplugging the sender (on top of the thermostat) and switching on the ignition (fan will spin to speed 1, then speed 2)

This also causes the engine warning light to illuminate. It is not cleared until the fourth time the engine is started.

So it seems I have a duff connection to the sender unit causing the EOBD to register an error and keeping the light on for the next 4 restarts.

I have given it the WD40 treatment in the hope it will fix it.

Unfortunately, now my temperature guage is working properly it seems my thermostat is actually stuck open and needs replacing. I will do a DIY job on it next weekend.

Thanks for the tip about the Ebay manual. I have bought one!

P.S. I hope this cold running may be why I had such poor MPG
 
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