P0231 - OBD Trouble Code

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The definition of trouble code P0231 is fuel pump secondary circuit low. This diagnostic fault code is a generic powertrain code, which means that it would apply to the OBD-II equipped vehicles. The specific repair steps can vary as it depends upon the vehicle make and model.

The engine control module would provide ignition positive voltage to the coil side of the fuel pump relay. When the ignition switch would be turned on, then engine control module would energize the fuel pump relay, which would apply power to the fuel pump. The fuel pump relay would be enabled by the engine control module as long as the engine is cranking or running and then the crankshaft pulses would be received. Now if no crankshaft pulses are received, then the engine control module would de-energize the fuel pump relay after 2 seconds. The engine control module would monitor the voltage on the fuel pump relay control circuit.

What causes this problem with the Fuel Pump Secondary Circuit Low?

• The fuel pump relay can be bad
• Harness chafing can cause open in fuel pump supply circuit
• The connectors might be loose or damaged
• Open in feedback circuit
• Fuel pump fuse can blow out due to short to ground

1. Fuel Pump - Do you remember when was the last time you got your car Fuel Pump checked up? A faulty Fuel Pump can cause a lot of issues like displaying P0231 code.
2. Fuel Pump Fuse - Poor Fuel Pump Fuse can cause a lot of difficulties, so why not get it replaced at time?
3. Engine Control Module - Are there some faults in your Engine Control Module? Don’t waste time and get them replaced or else P0231 code can turn up.
4. Fuse/Relay - OBD Code P0231 can appear because of faulty Fuse/relay.
5. Pin/Connector - Everything is fine with ECM and still P0231 code triggering? Then you must get your Pin/connector checked.
6. Powertrain Control Module - There can be some issues with the Powertrain Control Module due to which you may see P0231 code appearing over and over again. Visit us to buy best quality PCM online.

Our main motive is to achieve customer satisfaction and that’s why we will help you to diagnose P0231 code by mentioning some major symptoms below:

Common Symptoms

• No start and stall
• Engine misfire can start
• Inadequate fuel supply

Have a look at some ways with which you can correct the P0231 code:

If you want to diagnose fuel pump circuits there's no replacement for a good wiring diagram. You can always try to locate one before attempting a complex repair. If the vehicle will start and run and no driveability complaints are present, then you must suspect an open in the feedback circuit between the powertrain control module and where it splices into the fuel pump supply voltage circuit. You can always repair it if needed.

If the vehicle doesn't start or starts and dies due to low fuel pressure, then you should check the fuel pump fuse. If you find out that it is blown, then check for a short to ground on the fuel pump voltage supply circuit. Do this by removing the fuel pump relay and then check the resistance between the voltage supply circuit at the fuel pump connector and ground. If you have little resistance indicating a short to ground, the fuel pump should be unplugged and check it once again. If it shows high or infinite resistance after unplugging the fuel pump, replace the shorted fuel pump.

Now if the resistance is still low even after unplugging the fuel pump then repair short in the FP voltage supply circuit and if the resistance check is showing that the fuel pump supply circuit is okay then re-check between the FP fuse and the FP relay. There has to be a short somewhere. Carefully check for wiring harness chafing in certain areas. Repair as necessary. If the fuel pump fuse isn't blown and the vehicle won't start or starts and stalls due to low fuel pressure then remove the fuse and check that voltage is present to the fuse. After that you should check that voltage is travelling from the fuse to the FP relay by re-installing the FP fuse and checking for battery voltage at the FP relay. If the FP fuse or the FP relay doesn't have voltage supplied to it, the fuel pump will not be able to operate. Find the open in the circuit and repair as necessary. If both the FP fuse and the FP relay have sufficient voltage, remove the FP relay and install a fused jumper wire to complete the FP voltage supply circuit. Usually this is done by jumping terminals 30 & 87 in most relays-check a wiring diagram to be sure. If the fuel pump runs, replace the faulty FP relay and recheck. If the fuel pump doesn't run check for voltage present with jumper connected or by cycling the ignition key with FP relay installed at the fuel pump connector at the fuel tank. If voltage is present verify that the ground circuit is intact. If both are okay, then you should replace the fuel pump. If voltage isn't present at the fuel pump with fused jumper wire installed, then the open in fuel pump voltage supply circuit should be repaired properly.

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Here are some steps which you should follow in order to diagnose this fault code:

• The feedback circuit is the fuel pump secondary circuit that would provide input data about the primary fuel pump circuit to the powertrain control module
• A successful diagnosis of this code must include checking all related fuses and relays to ensure that the proper amount of voltage is present (typically this is a 5-volt reference signal)
• If you want to successfully diagnose this code, then you would require a scanner or code reader, a digital volt ohmmeter, and access to a manufacturer’s wiring schematic
• You should start your diagnosis with a visual inspection of all wiring and connectors
• The damaged, disconnected, shorted, or corroded wiring, connectors, and components should be repaired or replaced
• Make sure that you retest the system after repairs are completed to ensure success. If all system wiring, connectors, and components as well as fuses appear to be in normal working order, then you should connect the scanner to the diagnostic connector and record all stored codes as well as freeze frame data
• This information can prove to be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
• Now once the codes have been cleared, you should operate the vehicle to see if the code returns
• Now if the code fails to return immediately, then you may have an intermittent condition
• Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made. Test voltage at the fuel pump connector to determine if there is sufficient power and ground when the ignition key is in the start position
• If the required voltage is present at the fuel pump, then you should suspect a shorted or faulty pump and repair as necessary
• If there is no voltage at the pump or the voltage is reduced, then the problem is likely in the electrical wiring or connectors

Common Mistakes When Diagnosing The P0231 Code

Directly replacing the fuel pump can turn out to be a big mistake after seeing the P0231 fault code appearing