U3971 BMW Fault Code

Description:

BMW Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM).

If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored.

U3971 Code Symptoms :

The scent may U3971 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 U3971, 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 U3971

U3971 the main thing to check is to verify the operation of the VCT solenoid. You're looking for a sticking or stuck VCt solenoid valve caused by contamination. Refer to vehicle specific repair manual to perform component tests for the VCT unit.

How to fix U3971 code ?

• Failures of clutch motion/travel sensors.
• Faulty ignition coil (s)
• EVAP system hose leaking
• Failures of clutch motion/travel sensors.

Circuit High Input codes like U3971 are mostly caused by defective alternators that develop excessive voltages, although there may be other causes as well, such as short circuits that 'leak' current into a particular system from other, unrelated systems that work on higher voltages. Note that in the case of short circuits that leak power into a control circuit, there is likely to be other, seemingly unrelated trouble codes present along with the code(s) being investigated. Diagnosing a 'high input' code will always involve a thorough testing of the charging system as a first step, followed by measures to isolate the system from all other possible sources of power during resistance, continuity, and reference voltage tests.