View Full Version : ECT sensor problems.

06-10-2007, 06:29 AM
On thursday i noticed my coolant gauge going nuts and my car running like shit, i disconnected my CTS or ECT sensor and it ran fine, replaced it and had the same symptoms. The caris a 1998 A4 1.8T Quattro manual

I also noted when i disconnected the wires in the left hand plug from the gauge cluster that is fixed the porblem too.

I pull up certain codes, when the plug is connected, i pull up these codes all the time, same cylinder

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16688 - Cylinder 4 Misfire Detected
P0304 - 35-00 - -

When the sensor is dissconnected and it's running fine (No misfires) i pull up this codes

16502 - Engine Coolant Temp. Sensor (G62): Signal too High
P0118 - 35-00 - -

Now i've replaced the CTS with two new ones and it dose the same thing. Any suggestions? Thanks.

06-10-2007, 06:51 AM
Well, sounds like maybe it could be the cluster...

06-10-2007, 08:20 AM
I did some futhur research, and found out they may have given me the wrong sensor

well, you got that somewhat right

a blue sensor isnt "upgraded" to anything, a blue sensor is a dbc (ndbw, pre-00) sensor and is replaced by a blue top sensor, 059 919 501 and seal N 903 168 02

a black sensor is supposed to be replaced by a green top sensor, 059 919 501 A and seal N 903 168 02

they both read coolant temp for the ecu and the gauge

Is this correct? they gave me a green sensor saying the green was to replace the blue sensor.

06-10-2007, 09:46 AM
Hmmm... My car has a green top sensor by the head and a blue sensor on the hose that comes off the bottom of the radiator.

06-10-2007, 09:51 AM
Blue replaces blue. Green replaces black... Which sensor did you change too BTW?!

06-10-2007, 10:03 AM
My local dealer told me the green replaces the blue. So they gave me a green one and it plugs in normally. Don't the two diff sensors have different plugs?

BTW the sensor i am speaking of is at the back of the head. chris, mine is also a drive by cable, not drive by wire

Thanks guys.

06-10-2007, 10:19 AM
Is it a square connector or a D shape connector?

06-10-2007, 10:27 AM

06-10-2007, 11:36 AM
Part number on the sensor is Meyle 100-919-0043

06-10-2007, 04:48 PM
Problem solved, kinda. turns out it was defintly the cluster, traced wires for about an hour untill i realised i had access to Mitchell on Demand, if you don't know what it is, it ROCKS!!!!

06-10-2007, 10:20 PM
how did you fix it? is your car running better? i seem to be having problems with my coolant sensor and performance too...

06-11-2007, 06:36 PM
I ended up having to remove pins 7 and 8 from the left hand plug of the cluster, it was the gauge itself and should be your last resort. Check the resistance between pins 1 and 3.