B3971 BMW Fault Code

Description:

Intake Manifold Runner Control Malfunction (Stuck Open) The IMRC system is monitored for failure during continuous, key ON engine OFF or key ON engine running self-test. The test fails when the signal on the monitor pin is less than an expected calibrated range at closed throttle. IMRC monitor signal circuit shorted to BMW PWR GND or SIG RTN Damaged IMRC actuator Damaged PCM An IMRCM PID reading approximately near 1 volt at closed throttle may indicate a fault.

B3971 Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. B3971 code for the pushrod design which uses solenoids to alter the oil pressure delivered to the lifters. In their collapsed state, the lifters are unable to elevate their companion pushrods under the valve rocker arms, resulting in valves that cannot be actuated and remain closed.

Diagnosis And Repairing B3971

B3971 OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix B3971 code ?

• EVAP canister or fuel tank leaks
• Faulty spark plug (s)
• Exhaust gas leaks
• Ignition misfiring

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code B3971, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code B3971 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.