U1991 BMW Fault Code

Check U1991 OBD Fault Code Reason

Description:

BMW HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw.
The BMW test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S. Water in harness connector. Open VPWR circuit. Open GND circuit. Low battery voltage. Corrosion or poor mating terminals and wiring Damaged HO2S heater. Damaged PCM.

U1991 Code Symptoms :

The scent may U1991 signal oil or coolant leaking from their normally closed-loop systems, or it may indicate dangerous exhaust gases invading your car's interior. Car and truck exhaust contains toxic gases such U1991, so if the inside of your car as if you were standing behind your car, get out and get it fixed.
Fight the urge to take a little nap first. So sleepy. That's the carbon monoxide talking, friends. At least open a window on your way to the shop.

Diagnosis And Repairing U1991

Parts or components should not be replaced with reference to only a U1991 DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.