Location of coolant temperature sensor

Tiny
ALORTIE4
  • MEMBER
  • 1999 VOLKSWAGEN JETTA
  • 2.0L
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
I have:
1999 volkswagen jetta wolfsburg edition
Sedan four door.

2.0L I4 F

Problem: Temperature gauge stopped working and check engine light came on.
Two codes:
P0116 Engine Coolant Temperature (ECT) Circuit Range
P0442 Evaporative Emission Control System Leak Detected (small leak)

Computer recommends Standard Motor Products TS-477 Coolant Temperature Sensor as first pass repair.

Where is that sensor located? The actual part doesn't visually match the one on the top of the engine.

I'd like a schematic or photo please.
Friday, January 11th, 2019 AT 7:41 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,320 POSTS
Hi and thanks for using 2CarPros.

The coolant temperature sensor is located in the coolant flange on the driver's side of the vehicle mounted to the head. I attached a picture.

When you replace it, it is only held in with a plastic clip in the shape of a horse shoe. When you replace it, you must replace the o-ring at the base of the sensor or it will leak. When you replace the sensor and o-ring, make sure to check for leaks because they are common. If it leaks with the new o-ring, replace the cooling flange.

_______________________________________

As far as the EVAP code, small leak, I strongly recommend having the system fogged. A small leak is nearly impossible to find. What they will do is pump fog / smoke into the EVAP system at a very low pressure. The fog will leak from where the leak is located.

Let me know if this helps or if you have questions.

Take care,
Joe
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Friday, January 11th, 2019 AT 8:30 PM
Tiny
ALORTIE4
  • MEMBER
  • 2 POSTS
That was an awesome tip about fogging! Thank you! I will try that as soon as the weather goes above freezing around here! [they say by mid-week]
Another website says there's a 'cheat' on fogging using Gumout! See half way down at
https://tinyurl.com/y9bznhg3
I see the sensors that you indicate, but unless they gave me the wrong part, neither is the TS-477 Coolant Temperature Sensor. Are there others? Maybe fore and aft of the catalytic?
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Saturday, January 12th, 2019 AT 11:20 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,320 POSTS
Hi and welcome back:

I need to make sure we are talking about the same thing. When you say before and after the catalytic converter, most likely you are referring to oxygen sensors and not the coolant temp sensor. They wouldn't have an affect on how the temp gauge reads. Please confirm for me.

As far as the gumout test, that is to find an engine vacuum leak which is something totally different than an evap leak. The test they show can be found on our site for finding engine vacuum leaks. Here it is:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If you go to the following site, you will find many how to directions.

https://www.2carpros.com/articles

Now, the link I attached does not find EVAP leaks. With that in mind, it won't work for the problem your car has.

Let me know.

Take care,
Joe
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Sunday, January 13th, 2019 AT 10:36 AM

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