B0891 BMW Fault Code

Description:

Low Speed Fuel Pump Primary Circuit Malfunction The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM.
The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the BMW LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit). Open or shorted low fuel pump (LFP) circuit Open VPWR to low speed fuel pump relay Damaged low speed fuel pump relay Damaged PCM An open circuit or short to ground can only be detected with the low speed fuel pump.

B0891 Code Symptoms :

There are currently two main types of cylinder deactivation used today, depending on the type of engine. B0891 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 B0891

B0891 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 B0891 code ?

• Camshaft Position Sensor harness is open or shorted
• Clogged or faulty fuel injector (s)
• Continuous oil flow to the VCT piston chamber
• Failures of clutch motion/travel sensors.

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code B0891, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code B0891 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.