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Discussion Starter · #1 ·
Hi all.

Bit of a strange one. Bought the car about 8 weeks ago. Engine light was on from day 1. The car drove fine, no misfires/hesitations and perfect idle. I figured a faulty/bad sensor, possibly 02 and put it on the "to do list".

About 2 weeks ago I changed the thermostat. The temp guage now reads just under 90, I have hot air from the vents, and fuel comsumption is way better. Another job off the list.

Nearly a week to the day from putting the new stat in, the engine light suddenly went out. As I said, it had been there from day 1 of my ownership, and at this stage nearly 1500 miles of driving. It's been a week now and it's stayed off. Happy days :)

But I want to know why. The thermostat couldnt have been the problem could it ?
I havent done anything else major that could have effected it, apart from driven the car !

Or is this just another quirk of owning an Alfa ? :lol:

The short version? : Well , yeah.

A fault light does not actually need to mean that something is broken or not working, it often refers to a "value" that is out of the "given range" that the ECU parameters require, thus shows as a fault.

Changing the thermostat for example will have most likely meant that a temperature sensor is now working within its "given value" so therefore no more fault.
That will have a knock on effect with other sensors Like manifold air pressure (because the general engine temperature is now lower), MAF as the air will be denser in the plenum chamber than before with the decrease in ambient engine temperature and so forth.

Another likely explanation is that while changing the thermostat, you may have disturbed a sensor connection that was loose previously without you actually knowing:thumbs:

Just be happy that it works now :)
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