Diagnostic Trouble Code

P246B

Vehicle Conditions Incorrect for Diesel Particulate Filter Regeneration

What the code means

The vehicle is not meeting one or more of the conditions required for DPF regeneration.

P246B indicates that the conditions required for diesel particulate filter regeneration are not being satisfied. The code does not identify a single failed component; it tells us that regeneration cannot proceed correctly under the conditions being monitored.

Diagnosis therefore needs to establish which required condition is missing. Depending on the vehicle, this can involve engine operating conditions, temperature information, pressure information or hardware used to raise exhaust temperature during regeneration.

The Speed Tweaks video on this page follows a Ford Galaxy 2.2 diesel carrying P246B together with P2463. In that particular case, testing found a faulty exhaust fuel vaporizer, preventing the regeneration system from creating the conditions it needed.

Possible causes

What could cause P246B?

Regeneration temperature not being achieved

Fuel-vaporizer or regeneration fuel-dosing fault where fitted

Vaporizer glow-plug, fuse, wiring or supply fault where fitted

Relevant exhaust-temperature sensor or signal problem

DPF pressure or differential-pressure information outside expected conditions

Engine operating conditions preventing regeneration

Other engine-management faults inhibiting regeneration

Excessive DPF soot loading preventing normal regeneration strategy

Diagnostic approach

What should you check?

1. Read all related fault codes. P246B tells us regeneration conditions are incorrect, so accompanying faults can be extremely useful in identifying which condition is preventing regeneration.
2. Look at regeneration-related live data. Check relevant temperatures, DPF pressure, soot loading and regeneration status to establish what the vehicle is waiting for or failing to achieve.
3. Check whether exhaust temperature can rise correctly. If the system cannot generate the temperature required for regeneration, establish why rather than repeatedly commanding a forced regeneration.
4. Inspect the vaporizer system where fitted. On the Ford 2.2 diesel shown in the Speed Tweaks video, diagnosis included checking the vaporizer glow-plug fuse before removing and testing the exhaust fuel vaporizer and glow-plug arrangement.
5. Check DPF pressure. Assess the pressure across the DPF and make sure the pressure information itself is plausible. Excessive restriction may be both a consequence of failed regeneration and a factor preventing further regeneration.
6. Repair the reason regeneration is inhibited. Do not treat P246B as an instruction to replace one particular component. Correct the condition or system fault that is preventing regeneration.
7. Verify successful regeneration. Once the underlying problem is repaired and it is safe and appropriate to do so, confirm that the vehicle can complete regeneration and that the associated DPF faults do not return.

Speed Tweaks diagnostic video

Watch the P246B diagnostic process

Watch the Speed Tweaks workshop guide to diagnosing P246B.

Watch on YouTube →

A useful thing to remember

P246B is a useful clue, not a component verdict. In this Ford case the vaporizer was the cause; on another vehicle the reason regeneration is inhibited may be completely different.