How do you replace a coolant temperature sensor in 99 VW Passat?

Answer 1

Coolant Temperature Sensor Replacement

1998-2005 VW Passat 2.8l V6

Disclaimer: documentation for informational purposes only. No warranty is implied. Following these steps may lead to personal injury, death, dismemberment, mayhem, or voiding your vehicle's manufacturing warranty. Now, with that out of the way...

It is MANDATORY that you follow this procedure with the engine cool. Due to the proximity to the exhaust manifold (both the V6 and L4 engines) and the fact that you're working in the cooling system, you may horribly burn yourself if you attempt to do this on a hot engine.

Tools needed:

Stubby slotted screwdriver

Long slotted screwdriver

Small hands, preferably left handed (check child labor laws in your municipality)

Parts needed:

059-919-501A (Temperature Sensor- should have green plastic connector) about $4.00

N90136802 (O-Ring seal) about $1.00

032-121-142 (Spring) about $0.30

Total estimated time:

45 minutes

The coolant temperature sensor on the V6 Passat is located on a pipe that crosses between cylinder heads on the firewall side of the engine. There are a number things obstructing it. In this image, #7 is the sensor, #2 is the o-ring, and #6 is the spring clip.

You will need to remove the plastic cover over the intake manifold (A) by giving the 4 plastic screws 1/4 turn. Remove the air filter housing (B) (see the air filter replacement procedure for this), and disconnect the Mass Airflow Sensor (C) connector. Loosen the clamp on the far end of the flex pipe going into the intake (D). Gently pry the flex pipe off the plastic housing and slide it off. For future reference, the sensor is located around (E)

This is when it gets hairy, and the smaller hands will come in. It's a good thing my hands are small AND I'm ambidextrous. Make your own joke.

It's actually a little easier to remove the connector AFTER removing the sensor, so we'll concentrate on removing the sensor.

In this image, the arrow is pointing at the sensor itself. Look at what a pain this is!

Feel your way around here- your left hand works better (hence, a small left-handed left hand is the way to go) Look for the horseshoe-shaped plastic spring. This is all that holds the coolant sensor in place. Now, take the stubby slotted screwdriver and pry the horseshoe out about 1/4". Now, work the horseshoe out all the way.

Remove the sensor by pulling straight up. Make sure that it still has the O-ring attached. If not, stick your finger in the hole and see if the o-ring is in there. Make sure there's no grit in the sensor opening.

Attach the O-ring on the new sensor at the base, and insert it in the opening. Reinstall the horseshoe retaining clip. Reinstall the connector.

Put all the stuff you removed to get to this component (plastic cover, MAF sensor, air cleaner housing) back together.

The hardest part about this repair is the fact that you're working in extremely tight quarters. Still, it's fairly easy once you can get past that.

Note: the old sensor may have a black connector, while your replacement has a green connector. This is normal. The version with the black connector has a higher than normal failure rate (you probably wouldn't be reading this if you had the replacement green one) so make sure your replacement is the green connector version.