Engine Coolant Temperature Sensor Code

I got a code on the Jetta that comes up "Engine Coolant Temperature Sensor" then says the voltage is high. The check engine light comes and goes.

Where can I find the Engine Coolant Temperature Sensor on the engine?

Is it difficult to replace?

Thanks.

- Brian

Which engine? If it's the ALH it's down the back of the cylinder head on the gearbox end, a bit tricky to see.

I believe it's the ALH. It's a 2001 TDI Jetta. Thanks!

Is it too terribly hard to change?

- Brian

No it's pretty easy, there's a clip you slide out from the side (gearbox side) then whip out the old one with the plug attached, pop the new one in and secure it with the clip then get the plug disconnected from the old one and connect it up, once you've done that top up the coolant as needed. Did you find it?



It's easier if you remove the air intake pipe first

Seatman said:

No it's pretty easy, there's a clip you slide out from the side (gearbox side) then whip out the old one with the plug attached, pop the new one in and secure it with the clip then get the plug disconnected from the old one and connect it up, once you've done that top up the coolant as needed. Did you find it?

It's easier if you remove the air intake pipe first

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Thanks! Looks easy enough! Fixing this sensor will probably fix my limp mode problem.

- Brian

Doubt it, the coolant sensor just ups the revs at idle, glow plugs stay on longer and the engine runs in cold settings making it a bit noisier. Wont affect limp mode, that's a boost problem anywhere from the maf to the inlet manifold and anything in between.

Seatman said:

Doubt it, the coolant sensor just ups the revs at idle, glow plugs stay on longer and the engine runs in cold settings making it a bit noisier. Wont affect limp mode, that's a boost problem anywhere from the maf to the inlet manifold and anything in between.

Click to expand...

Hmmm... When I was reading here about what causes limp-home mode, it said that sensors reading wrong can cause it. It says to check the computer for codes and fix those and this can possibly fix the limp-home mode. The only code I'm getting at the moment is the Engine Coolant Temperature Sensor code that says it's reading too much voltage, or something to that effect. Sounded like that would qualify as the cause of the limp-home mode. I'm a little bummed now... I didn't want to spend more money on this car before I sell it.

So, you say it's a boost problem.

- May I ask how sure you are of that diagnosis?

- Also, what would you say are the biggest causes to check first?

- By the way, the MAF was replaced less than a month ago. I assume that's not it, but the previous owner did say that there was about three hesitations/skips that felt like a gas engine missing while driving on the highway right after he had the MAF changed. Is it possible the new MAF is bad and causing the problem, or would you check elsewhere for the problem?

- Finally, what would you say is the best way to diagnose the problem quickly to minimize time and cost?

Thanks so much!

- Brian

You may want to find a guru in the DFW area from this list: https://docs.google.com/document/d/1Lucw8ALCkLtt79MMw9JOG1E_dX57-raBhbhIFdtHnEQ/edit?hl=en_US&pli=1#