DME Temp Sensor

[heung]

I heard the DME Temp Sensor mentioned many a time. I was wondering where is this sensor located. I believed it has something to do with hot and cold starting by controlling the fuel. Am I correct?

[Vandit]

I'm guessing you're referring to the cylinder head temp sensor.

I believe you can test the functionality using a Bosch Hammer or a T-OBD diagnostic tool plus scantool program. You can basically see if it is registering a temperature.

The actual sensor is located on the back of the #3 cylinder. Access is through the fender well. It has a rubber plug where it goes through the engine tin and it shares a wire grommet w/ the flywheel sensor wiring. You also need to disconnect it at the bracket that is on the left rear part of the intake plenum.

You'll need an O2 sensor socket to remove it or buy a deep socket and use a Dremel cutoff wheel to cut a slot all the way up the side for the wire.

[hrscrk]

vandit: i have a similar question. can i reach u by fone. you can email me at hrscrk@mcn.net

thanks.

[ischmitz]

The 964/993 have two temperature sensors. One monitors the cylinder head temperature (CHT) and the other the intake air temperature (IAT). The CHT is located on the drivers side cylinder head closest to the fire wall. Kind of hard to get to, you need to get under the car. The IAT sensor is integrated into the AFM (964) or MAF (993). Both sensors are used to calculate fuel mixture. On the 964/993 the DME is smart enough to figure if the values provided are plausible. In case of a fault (open or short) the DME will assume a fully warmed up engine as default which makes it tough to cold-start or run when cold.

As others said you can use a Porsche diagnostics tool (PST2 or Hammer) or an aftermarket diagnostics tool (Durametric) to read the sensor values seen by the DME. You can also flash out fault codes from model year 91- by simply using the CEL as indicator. This will tell you if there is a fault stored in the DME related to the temperature sensors.

Cheers,
Ingo