Hi guys,

 

A quick one, are there more than one temp sensor on the 1.4 16V 75hp (BBY) engine? One for engine management and one for temp gauge in the dash, or is the one mounted in the thermostat housing used for both?

 

Just one.

There's also a thermoswitch in the radiator which controls the fans.

What's the problem?

Edited 12 October, 20187 yr by Wino

18 minutes ago, Wino said:

Just one.

There's also a thermoswitch in the radiator which controls the fans.

What's the problem?

 

Thanks for the quick answer!

 

Well, the problem isn't the sensor then, as it shows normal operating temp in the dash. Exhaust emission readings was a bit high last MOT, so I thought maybe the sensor was faulty. Guess I'll do nothing about it though, since the readings were below legal limit. Maybe the catalyst has deteriorated or something. Or are there other common issues that can affect emissions? There are no DTC's.

No problem.

Which reading was high, CO or HC?

The electronics in the dash does 'feelgood' the data to some extent before displaying it on the gauge.  I think it shows 90 from about 70 upwards, not sure what temperature the coolant has to get to before it shows more than 90.

If you have access to VCDS, try reading coolant temperature directly from the engine ECU, which is what reads the sensor. The data is then passed around to any other interested modules via CAN.

 

My BBY had high (half the legal limit here) HCs for a few MOTs which didn't go up much from one to the next.

I think I replaced the pre-cat before the last one and saw the level drop down considerably. As you say, probably deterioration of the cat.

Both were high, CO ~0.3 and HC 120. Thought it would fail since the limit has always been 100 ppm, but the guy told me they increased the limit to 200 ppm in May (I live in Sweden, maybe you have other limits). Sounded very strange to me, but I don't complain

 

No VCDS yet, unfortunately. Will ask on the Swedish forum if anyone in my neck of the woods have it, but that forum isn't very active. Briskoda is waaaaay better! 

 

Thanks for your help!

I would suggest cat deteriorating....

 

but if your car has two lambda sensors & two cats....my AUB .4 16v did...

 

then if the last lambda sensor is not seeing the correct % scrub of the gases from the cats due to cats deteriorating it should also trip a fault code in the ECU....