B0129 Trouble Code

View B0129 obd/2 error code description and symptoms. B0129 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.

A good starting point in your diagnosis is checking all system fuses and fusible links. This can be done using the DVOM on the voltage setting. You will want to test the fuses with circuits loaded. Some fuses will appear normal until a load is placed on their respective circuit; at which point they will fail. This has been the cause of many 'phantom malfunctions'. Consult your vehicle information source for fuse and fusible link locations. If all fuses are in working order, you may want to check TCM relay operation by swapping identical relays. Usually the horn relay, starter relay, fuel pump relay, air conditioning clutch relay, and controller relays are similar enough in design to swap for diagnostic purposes.

Difficulty Level (Expert)
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Repair Time (60 Min.)
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Cost Prediction : $ 40-60

B0129 Error Code Repair Process :

OBD B0129 code and tailpipe testing are two different approaches to identify vehicles in need of repair. The OBD system looks for broken or malfunctioning emissions control components and cylinder 1 misfire detected, while tailpipe tests sample a vehicle's exhaust to see if it is above or below certain prescribed limits. Given the robust nature of today's emissions control components, it is entirely possible for an individual component to B0129 malfunction without leading to an immediate increase in emissions at the tailpipe. In such cases, other components (like the catalyst) can temporarily compensate for the part that is broken however, these other components can only do double duty for so long before they, too, begin to malfunction. In addition, OBD also monitors for B0129 and other malfunctions in the fuel system problems that traditional tailpipe tests were not designed to identify. Most state and local areas also include a gas cap pressure test as part of an emission inspection.

Wrench Tool B0129 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 B0129

A common cause of code B0129 is the failure of Cylinder 1 Misfire Detected, but there are several other possible causes as well, such as ;

B0129 code for all cars

You can view according B0129 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+B0129 Honda Accord +B0129 Daihatsu Terios 2 +B0129 Bertone Stratos +B0129 Chevrolet Trailblazer 2 +B0129 Volkswagen Golf 4

Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.

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