Fault code P268B is called “High Pressure Fuel Pump Calibration Not Learned/Programmed” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P268B
OBD-2 code P268B is most commonly defined as “high pressure fuel pump calibration not programmed”. It is set when the PCM has received information about a failed high pressure fuel pump (HPF) calibration or adaptation.
This error is most often found on Ford Transit vehicles when the fuel injection system is taught or calibrated. The fault may be either software or mechanical.
With a mechanical fault, the high pressure fuel pump may not be working, so the calibration fails. With a software error, respectively, there is an adaptation failure, so the programming fails.
Therefore, the PCM activates error code P268B when it monitors one or more conditions after calibration or adaptation. This can be caused by a mechanical or electrical problem.
Symptoms of vehicle malfunctions
The main signal that an error P268B has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related fault codes may also be present.
- The engine may fail to start or may start and then stall.
- Floating revolutions, and attempts to stall while idling.
- Insufficient fuel supply due to improper fuel pump operation.
- Reduced power output of the engine.
- Increased fuel consumption.
- Presence of fuel odor.
- Engine stalls when reaching operating temperature.
- There may be no symptoms other than a stored fault code.
Failure related to fuel pump calibration may cause problems with engine starting, so error P268B is considered serious. If it is ignored, components may fail completely.
Factors that can cause this error code
The error code P268B can mean that one or more of the following problems have occurred:
- Faulty fuel pump.
- Incorrect calibration or adaptation.
- Fuel pump relay is faulty, and no voltage is supplied to fuel pump.
- Damaged wiring harness leads to breakage of fuel pump power supply circuit.
- Loose or damaged connectors.
- The feedback circuit is open.
- Fuel pump fuse blown due to short to ground.
- Defective CAN bus line.
- Sometimes faulty PCM module is the cause.
How to fix or reset OBD-2 code P268B
Some suggested steps for troubleshooting and fix the error code P268B:
- Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P268B appeared.
- Clear the error codes from the computer memory and test-drive the vehicle to find out if the fault appears again.
- Perform a calibration or adaptation with a proper scan tool.
- Test the fuel pump module.
- Check that the fuel pump is working properly.
- Test the fuel pump relay.
- Visually inspect electrical wires and connections for looseness and damage.
- Check the inertia switch, turn it on if necessary.
- Replace fuse if necessary.
- Clear the error code from the computer memory again, test drive the vehicle to see if the problem is resolved.
Diagnose and repair of problems
To diagnose the fuel pump circuits and clear the P268B fault code, you need the wiring diagram for your vehicle. After that you can proceed with further actions.
If the car starts and drives, no steering complaints, most likely there is a break in the feedback circuit between the PCM and the fuel pump supply voltage circuit. Repair if necessary.
When the car won’t start or starts and shuts down because of low fuel pressure, check the fuel pump fuse. If it is blown, check the fuel pump supply circuit for a ground fault.
Remove the fuel pump relay (FP), and then check the resistance between the fuel pump connector voltage circuit and the ground. If there is a small resistance indicating a ground fault, disconnect the fuel pump and check it again.
If the fuel pump shows high or infinite resistance after disconnecting it, replace the shorted fuel pump. If the resistance is low after disconnecting the fuel pump, repair the short in the FP supply circuit.
After checking the electrical circuits, there will likely be several scenarios. Either the P268B error will go away because the wiring problem has been corrected. Or the problem is a faulty relay, module, or fuel pump itself.
Most often the error P268B appears after an improper adaptation of the fuel pump, or with the help of improper scanners. The best way out is to adapt it with the help of a service scanner or in a specialized workshop.
On which vehicles does this problem occur most frequently
Fault code P268B can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Ford (Transit)
Fault code P268B can sometimes be found with other errors. The most common are the following: P025A, P025B, P025C, P025D.
