Temperature sender fault

[doc]

I know I have a faulty temperature sender on my 2001 Bora 2.0. It has an intermittent fault where it reads cold, 1/4 or where it should be on 90. I have tested the gauge and it's OK.
My question is, if the temperature sender is faulty, does it send a signal to the ECU saying the engine is cold and consequently richens the mixture? It's a green top sender and will be replacing it in the next few days. Just curious if it does talk to the ECU.

thanks.

[Lams]

you could use a diagnostic tool on your instrument cluster to see what it thinks the temp is. Then you'd know whether it's the gauge or the temp sender!

[doc]

I've already tested the gauge and it's ok. I know it's the sender. Just curious if the faulty sender richens the fuel mixture by telling the ECU the engine isn't hot.

[h100vw]

The sender is effectively 2 sensors, one for the gauge the other for the ECU. A scan with VAG-COM would tell you if the half feeding the ECU was intermittent. It would make it run rich if it was 'cold'.

For the cost of a new one though, I'd just fit one.

Gavin

[sierra055]

As Gavin said above, 2 wires are for the ECU, 2 are for the internal gauge.
I had some faults coming up on my car indicating an implausible coolant temp, even though the gauge read normally. My symptoms were that the car wouldn't start when hot cause the ECU was making the mixture too rich and was flooding it.

[doc]

Thanks for the replies. It did come up with an intermittent fault on the vag com. (I've only got the unregistered one at this stage) I was going to replace the sender in the next few days anyway. Curiosity got the better of me regarding the fuel and ECU. It is my first VW in 31 years of owning cars and I'm still getting to know them.

[dubbed]

I replaced mine and got slightly better economy. Mine was the old black style though.

[Oneofthegreats]

Even though the "green" top sender unit's are the modified version, they can still give troubles.

Also the answer to your question is yes, it can cause the engine to run rich as it think's the engine is alway's cold & dump's fuel in there.

[goodfella]

I can vouch for the black to green update. I had a similiar fault code in VAGCOM and replaced it with a locally supplied unit (thanks Loon) . 10 min job to do, just remember to release the pressure by removing the cap on the reservoir.