5v/cyl

Right. First step is to see if it is gauge problem or is it really running hot. The CTS (coolant temp sensor) is two sensors in one. One side of the sensor tells the ECU what the engine temp is and the other side tells the gauge what the temp is. With the VAG-COM go to 'Engine module' and look at group 1. Coolant temp should be around 87C when fully warmed. Also look at 'Instruments module', not sure which group, and see if the reading is the same for coolant temp. If one is way different then the the CTS is bad.

vtraudt

I assume same engine module can be used to run output test on the V7 and V177 fans (while I am at it).

vtraudt

Got my hand on the car yesterday and hooked up VAGcom:
Engine module coolant temp: 57 deg C
Instrument module coolant temp: 121 deg C

So: CTS bad?
Correct search term for CTS or part number (2002 Allroad)?
Where is the CTS located so I can prepare for the change?

Thanks.

Zuffenhausen951

Sorry to revive old thread - but the CTS is causing a false overheat condition. Looks like the differences between the gauge and actual coolant temp, is about one tick too high. This alone will shut A/C compressor off, due to the threshold of gauge-driven, A/C function is below 105C. OP, it also appears your auxiliary electric fan is shot, if not running with the air on. Even at above 95C on the coolant gauge - the aux fan should be running even with the A/C OFF.

Only will the fans switch to Hi-speed....when the engine is near overheat conditions(above 110C).

vtraudt

I replaced the CTS and everything was back to normal.
Not sure if that alone caused 'limp mode', or if (on that car) faulty EGR temp sensor was the culprit (also fixed at same time; limp mode gone).

Douglas Briscoe

2002 2.7t
When outside temp exceeds 90degrees, engine starts to over heat. Large oil light comes on.

Checked oil level - good
Checked coolant level - good
electrical fans working
belt driven fan rotating

Problems started after oil and filter change - used Mobil One Syn 5w-30w

Probably coincidence

Suspect sticking thermostat.

Comments?

Zuffenhausen951

Doug, don't get the oil warning and coolant warning mixed-up. Verify on the Owner's Manual, which is the correct dash warning.

awdjunkies

Correct, use this for reference..

vtraudt

What gets hot. Oil or Coolant?

If coolant: is it just the display or REALLY hot (water boiling)?
What are VAGcom temperatures saying?

"Got my hand on the car yesterday and hooked up VAGcom:
Engine module coolant temp: 57 deg C
Instrument module coolant temp: 121 deg C"

AllWorld

Just had similar issue - 98F degrees outside - lots of traffic and all fans running (clutch fan converted to electric supposedly 2200 cfm) Anyway - as long as I was moving I was right in the middle on the temp gauge - once stopped the gauge would climb by 1/4 - it held there so I wasn't too worried - figured it was the max efficiency of all the aftermarket electric fans (I changed them all due to defects and did not go with oem (oops?)) - then the gauge over time climbed within 1/4 of max - extremely worried now - never ever got that high before - no warnings of any kind - oil temp went about 2 ticks over 250 - never had that before either - but once at highway speed - everything goes back to proper temps. my 1st thought was underrated fans - but I'm not so sure - new temp sensors were installed too (not oem) - so I will follow steps on VAG-COM - let you know the outcome - but at first blush - what would you think is the problem? 154k - 1st owner said oil change was due 157k and timing belt at 175k - I usually never listen to people selling their cars but he seemed on point. When I finally went thru the repair records he provided I didn't see the 1st timing belt change so I may be in trouble. BTW - my oil dipstick was dry after stopping the car for a while and checking - maybe it didn't have enough time to drain back into the oil pan but it shouldn't take that long anyway. WORRIED!