Check Engine Light - Thermostat problem

[kapil403]

My check engine light was on and I got it vagged. The shop told me that the problem is with the thermostat. The engine temprature has been showing fine on the dial. I got it reset and it came back on again after a few days.

1) Any thoughts?
2) Cost to get it replaced.

Thanks a lot for your help.

[manguyen]

with the thermostat, you fan should come on when you first start the car... it loud as hell too. This was how my car acted with a thermostat problem.

[Elberoth]

Just replace it. It is dirt cheap. I replaced mine (I have 80k miles on my car) 2 months ago for the piece of mind.

[manguyen]

wait? how is our thermostat dirt cheap? i paid about $100 bucks for it. most car thermostats are like 10-15 bucks

[diagnosticator]

My check engine light was on and I got it vagged. The shop told me that the problem is with the thermostat. The engine temprature has been showing fine on the dial. I got it reset and it came back on again after a few days.

1) Any thoughts?
2) Cost to get it replaced.

Thanks a lot for your help.

What was the exact DTC number the scan revealed stored in the Fault memory?

If your A4 is a 1.8T, the TStat, has a heater element inside, controlled by the ECU, and varies the engine temperature depending on engine load/speed maps programmed in the ECU. A replacement TStat, costs about $100+
The only DTCs referring directly to the TStat, involves a failed heater element inside the assembly, or an electrical fault with the circuit connected to the heater.

[A4TL]

bet its the coolant flange and green cts!

[Elberoth]

wait? how is our thermostat dirt cheap? i paid about $100 bucks for it. most car thermostats are like 10-15 bucks

Sorry, you are right. That was a coolant temp sensor that was dirt cheap (15$ or so). I replaced several sensors all at once, chence the mistake.