B3903 Trouble Code

View B3903 obd/2 error code description and symptoms. B3903 engine photo

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 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.

As the engine heats up and combustion becomes easier and more complete, the PCM will command the idling control valve to increase the amount of air entering the engine to suit the changing conditions. However, when the load on the engine changes, say, when some electrical consumers or other systems are either turned on or off, the PCM adapts the signal voltage to the idle control valve to ensure that the idling speed remains stable, and at the RPM specified by the manufacturer.

B3903 Error Code Repair Process :

If your ignition tach circuit failure 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 B3903 and engine control unit are in charge of monitoring a bunch of different ignition tach circuit failure, and if they get a reading that's a little out of whack, up pops the check engine light.

B3903 is a kind of Body Trouble Code

Auto body problems aren't always easy to spot. Diagnosing auto body problems sometimes requires a little know-how. In this section you'll find articles dedicated to teaching you how to diagnose auto body problems.

Common Causes of B3903

A common cause of code B3903 is the failure of Ignition Tach Circuit Failure, but there are several other possible causes as well, such as ;

EVAP canister or fuel tank leaks
Faulty ignition coil (s)
Fuel filler cap remains open or fails to close
Faulty oil control valve (OCV)

B3903 code for all cars

You can view according B3903 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+B3903 Alvis Tf21

+B3903 Chevrolet Vega

+B3903 Alfa Romeo 179

+B3903 Volkswagen Atlas

+B3903 Honda Model

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