G62 Coolant sensor problem

[Carfreak]

Hi! Just wounder if the G62 - Short to ground is a fault on the sensor or at the wiring!?

Checked the wiring before and there were no problems there..

[UrS4boy]

G62 coolant temp sensor info

Link:

http://forums.quattroworld.com/s4s6/msgs/20985.phtml

From:

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

[Carfreak]

Thnx! So I just measure the sensor with the coolant at room temp ?

[UrS4boy]

Thnx! So I just measure the sensor with the coolant at room temp ?

From Bentley, the G62 (Engine Coolant Temperature (ECT)) sensor test procedure is as follows:

Allow the engine to cool to room temp (68F/20C)
Disconnect ECT sensor from harness connector
Switch multimeter to resistance range
Connect multimeter to terminals 1 and 2 of the ECT
Resistance must be 1500 to 3000 ohms

IF NO = replace ECT
IF YES = check wiring between sensor and ECM (ECU)

[Carfreak]

From Bentley, the G62 (Engine Coolant Temperature (ECT)) sensor test procedure is as follows:

Allow the engine to cool to room temp (68F/20C)
Disconnect ECT sensor from harness connector
Switch multimeter to resistance range
Connect multimeter to terminals 1 and 2 of the ECT
Resistance must be 1500 to 3000 ohms

IF NO = replace ECT
IF YES = check wiring between sensor and ECM (ECU)

Okey, thnx! I hope there´s nothing wrong with the wiring.. Could I test to connect the sensors ground to the chassi to see if the fault is in the ground wire ??

[newsh]

Often the wire is broken just near the sensor, maybe under the rubber boot. Or the pins in the plug may be corroded.

[UrS4boy]

Okey, thnx! I hope there´s nothing wrong with the wiring.. Could I test to connect the sensors ground to the chassis to see if the fault is in the ground wire ??

The G62 is a temperature-influenced variable resistance. The ECU drives out a voltage (5V? 12V?) to the G62 via ECU pin T45/55 via a Grey with Brown stripe (GY/BR) (maybe a brown with greystripe) wire. The return current is returned to ECU ground pin 30 (via green with a black stripe wire for an AAN not sure about ABY or ADU).

[Carfreak]

Well see how it goes.. Ordered a new ecu water temp sensor and will be replacing it today..

My symptoms are: Irratic idle and sometimes the engine stalls. The AFR value jumps from 14,7 to 15,5 at idle. Unable to hold a steady rpm, the rpm goes up and down 2-400rpm and has kinnda slow throttle response...

Hopefully this is because of a bad sensor or a wiring issue!

The symptoms only accour when the engine reaches about +50C and above.. not when cold start..

I just measured the sensor.. I´ve got 570 Ohm.. I´ll try to measure it again when the engine is cooler..


Reacieved the wrong sensor.. didn´t fit.. what´s the oem number on the sensor for AAN ?

[UrS4boy]

I just measured the sensor.. I´ve got 570 Ohm.. I´ll try to measure it again when the engine is cooler.. Reacieved the wrong sensor.. didn´t fit.. what´s the oem number on the sensor for AAN ?

Resistance needs to be 1500 to 2000 Ohms at 20 deg C.

PN = 035919369M as identified in the G62 post link I provided you on Sunday:

http://forums.quattroworld.com/s4s6/msgs/20985.phtml

[prj]

If you are on Motronic ECU then your symptoms are not caused by the sensor.

[UrS4boy]

If you are on Motronic ECU then your symptoms are not caused by the sensor.

They are caused by.....?????

[Thuppu]

I have had the same symptons from day one when I bought the car. Just so you know Dmitri when you come here to remap. Anything I can do to get rid of it?

[prj]

Can be a multitude of issues, but if it won't idle right, then first culprits are all kind of vacuum leaks, crappy ISV's and so on.
I do hope you pressure test it Thuppu

As for AFR's jumping momentarily towards lean, that's just misfire.
A side effect of the crappy 630cc dekas the OP is running.

[Carfreak]

Can be a multitude of issues, but if it won't idle right, then first culprits are all kind of vacuum leaks, crappy ISV's and so on.
I do hope you pressure test it Thuppu

As for AFR's jumping momentarily towards lean, that's just misfire.
A side effect of the crappy 630cc dekas the OP is running.

Really really strange since I just changed out the G62 and the engine runs smooth without afr and rpm jumps

So just so u know.. Deka´s ain´t the cause of all problems!

And yes I´m runnin motronic at the moment..
The isv is new, no vakuum leaks upto 2bar and the ecu temp sensor was broken since Id got wrong measured value!

[Carfreak]

Resistance needs to be 1500 to 2000 Ohms at 20 deg C.

PN = 035919369M as identified in the G62 post link I provided you on Sunday:

http://forums.quattroworld.com/s4s6/msgs/20985.phtml

The resistance were 800 Ohms at 20 deg so it was bad

My vag dealer didn´t use that part number anymore but I found it anyway