My service engine soon light came on and its saying emissions increase on the dash,whut do dat mean?04 530i
Thermostat can cause emissions light if it is stuck open (engine won't warm up fast enough) or if the heater coil is broken (ECU tests the heater coil circuit on start up). I had a heater coil fail, and you can measure the resistance of the heater coil to eliminate that as a possibility. Pull the connector off the thermostat and measure the resistance between the two contacts - normally measures around 16ohms, but if it measures 1 (open circuit) then it is gone. A broken wire in the harness leading to the thermostat will also cause the same fault but it is rare.
CHECK (http://5series.net/forums/e60-discussion-2/increased-emissions- warning-light-139742/)
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