Error Code P0116 question

[WriterJWA]

Yesterday I switched my coils to Hitachi E's and changed the spark plugs to NGK's. I seem to be running ok, but this evening I threw four codes, all of which seemed to have nothing to do with the coils directly. I cleared them, then later the CEL came back on with this one code, which is repeated from earlier:

Address 01: Engine
Controller: 4B0 906 018 M
Component: 1.8L R4/5VT G 0002
Coding: 16251
Shop #: WSC 06335
1 Fault Found:
16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-10 - - - Intermittent
Readiness: 0000 1001

Does this mean that the coolant sensor is toast? The engine temp gauge seems to work fine. Or is this a bad connection?

[biketsai]

Itll help to search the code, even check out wiki.ross-tech.com for all of these codes. Posting your codes in one thread might help out too.. Here ya go

Possible Symptoms
Starting the engine when engine is warmish or warm, idle rpm immediately is 1200 - 3000 rpm.
Diesel: an indication is extreme long time burning time of the glow indication light.
With all engine temperatures seldom idle rpm will vary between 900 - 1000 rpm.
With engine warm (90 °C) the engine temperature suddenly drops (70 °C) and slowly comes back to 90 °C.
Possible Causes
Wiring and/or connections faulty
Engine Coolant Sensor (G62) faulty
Possible Solutions
Check wiring and connections
Replace Engine Coolant Sensor (G62)
Special Notes
In MY 1995-2002 (?) in Europe at VW-cars the G2/G62 had the bad reputation of breaking down often. The default G2/G62 is black and all replacements are green.
Check if the correct Coolant Fan Control Module/Relay is installed (check part number using parts catalogue)!

[walky_talky20]

Does this mean that the coolant sensor is toast? The engine temp gauge seems to work fine. Or is this a bad connection?

Yes, replace the sensor. The sensor itself is actually 2 sensors in 1. One "leg" or "side" of the sensor is for the gauge on your instrument cluster. The other side is for the ECU. So the readout on your gauge is not *necessarily* what your ECU is seeing. The different sides of the sensor can fail independently, together, intermittently, or all at once. It has license to fail however, whenever, and however often it would like.

[WriterJWA]

Yes, replace the sensor. The sensor itself is actually 2 sensors in 1. One "leg" or "side" of the sensor is for the gauge on your instrument cluster. The other side is for the ECU. So the readout on your gauge is not *necessarily* what your ECU is seeing. The different sides of the sensor can fail independently, together, intermittently, or all at once. It has license to fail however, whenever, and however often it would like.

So I've noticed. I cleared the code (again) out of curiosity and after both driving last night and to work this morning it has yet come back (knock on wood).... so we'll see. I found the sensor on the engine block, but it's underneath a bunch of EGR crap and looks like a pain to get to.

[walky_talky20]

Yeah it is a bit more tricky to change on the '01's because the combi valve is more in the way than on earlier 1.8T's. It takes like 10 min instead of 5.