U3138 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.

U3138 Code Symptoms :

If your U3138 check engine light is illuminated, it's best to take it in for diagnostic testing, which can feel like a hassle. Because while the lights vary in appearance from vehicle to vehicle, all have the same basic meaning: There's a problem with the car's emissions system. The on-board diagnostics system U3138 and engine control unit are in charge of monitoring a bunch of different , and if they get a reading that's a little out of whack, up pops the check engine light.

Diagnosis And Repairing U3138

U3138 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 U3138 code ?

• Camshaft Position Sensor harness is open or shorted
• Damaged ECM
• Fuel injectors harness is open or shorted
• Faulty oil control valve (OCV)

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code U3138, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code U3138 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.