Mk30 golf temp sensor reads 110 steady.....

[domh30]

HI a mate has a 93 1.8CL auto which has just failed the MOT, his garage are ripping him off (want £1200 to put it through when it failed on high lambda, a hole in the exhaust, headlight alignment and wipers)!

Anyway said I would take a look.

A while ago he overheated and had a water pump which they replaced with the cam belt. However ever since then he says the water runs at 110 degree’s. Told him to return it to the garage who say this is fine (WHAT?).

Anyway am guessing that the car is in fact fine but the temp sensor went when it originally over heated, he has done about 3000 miles with the sensor reading 110 which seems pretty good going if the car is actually running that hot!



Would this also be enough to tell the engine to run lean and cause lambda to go over?

The emissions passed on both CO and HC and yet lambda fails, so if not I am guessing the sensor of worst case the cat.

Anyway am having a look at the weekend advice in advance would be appreciated.

Thanks

[a8 tech]

yes the temp reading will have an impact on the lambda and cooling fan intervention will also alter the reading,the hole in the exhaust will also have a part to play but if co and hc are ok i would suspect the cat isnt converting.It was possible on early engines to test emmisions before the cat and a blue seal off plug was inserted on the exhaust manifols were you coulld attatch the emmisions reader and see the pre cat readings then goto the back and see the post readings.If i remember correctly if the emmissions failed on the incresed idle and co hc ok is was nearly always the cat,again a voltmeter accross the lambda will tell you what the lambda is seeing the lambda lean or rich.