P24AF
System
Powertrain (Diesel Emissions)
Scanner required
Full-system scanner (engine, ABS, SRS, transmission, service resets)

Particulate Filter Regeneration Incomplete

Understand P24AF, common causes, and the right TOPDON scanner to diagnose it.

DPF regeneration started but did not complete successfully.

Common symptoms

  • Soot level still high after regen attempt
  • Check engine light

Typical causes

  • Stopped mid-regen by driver
  • Fault aborted regen
  • Insufficient fuel dosing
  • EGT too low during regen

What scanner do you need?

Full-system scanner (engine, ABS, SRS, transmission, service resets)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose P24AF with a basic code reader?
P24AF may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with P24AF?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.