BMW E30 temperature gauge not working or reading wrong
E30 temperature gauge does not rise or reads wrong – how do I test it?
With the ignition on, connect the temperature sensor wire to ground. If the needle jumps to full red, the gauge is fine and the fault is in the sensor. If the needle does not move, the fault is in the instrument cluster or the wiring. The temperature gauge alone can be replaced separately.
Why does the E30 temperature gauge go straight to maximum or fluctuate?
Somewhere in the wire may be grounding, so check the whole wire and the sensor. The cluster's connector contacts and solder joints can be cracked off the circuit board, and resoldering the joints has restored the gauge's function. Fluctuation can also be caused by the cluster's connections.
Where should the gauge be while driving?
With a warm engine the needle is normally in the middle or slightly below halfway. A needle rising to red in traffic is always a fault: usually the viscous coupling, air in the cooling system or the thermostat. The gauge reading can be verified with a separate thermometer.
What kind of temperature sensor does the E30 have and where is it?
The cluster's sensor is single-pole (e.g. brown on the M20), on the M40 it is two-pole. On the M10 it is in the intake manifold under the intake air hose. The M20 injection control unit's sensor is blue and is located in the thermostat housing, right below the cluster's sensor.