P24F6 code meaning
Exhaust Aftertreatment Fuel Air Purge Valve Stuck Open
Powertrain system Generic code P24xx codes Check engine light
What P24F6 means
Heavy Volvo and Mack trucks regenerate the particulate filter with an aftertreatment hydrocarbon injector (AHI, the 7th injector) that sprays diesel ahead of the oxidation catalyst; compressed air from the truck supply then blows the line to the nozzle clear. P24F6 means the fuel/air purge valve in the AHI module seems to stay open, so air keeps flowing when it should not. Solution K17696792 (US15 and later, 11, 13 and 16 L engines) lists checks when guided diagnostics finds nothing: 32 psi (221 kPa) at the doser air supply, a dry purge line, the right coalescing air-dryer cartridge and no aerated fuel. For the open case Volvo's AHI guide also replaces the nozzle and cleans the line. Regeneration can fail and soot builds up.
P24F6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P24F6
- Particulate filter regeneration does not complete
- Warning lamp and aftertreatment message on the dash
- Rising soot load and more frequent regeneration requests
Common causes of P24F6
- Most likelyOil or water in the purge air from an unsuitable or worn air-dryer cartridge
- PossibleDebris holding the purge valve in the AHI module open
- PossibleDamaged AHI nozzle or leaking fuel/air line toward the nozzle
- Less likelyDoser air supply pressure outside the 221 kPa specification
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aftertreatment purge valveDosing line
What each part of P24F6 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| F6 | The exact fault in that area. |
What to do next
- Note P24F6 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P24F6
What does P24F6 mean?
P24F6 means "Exhaust Aftertreatment Fuel Air Purge Valve Stuck Open". Heavy Volvo and Mack trucks regenerate the particulate filter with an aftertreatment hydrocarbon injector (AHI, the 7th injector) that sprays diesel ahead of the oxidation catalyst; compressed air from the truck supply then blows the line to the nozzle clear. It is a generic code, so it means the same on every make.
Is it safe to drive with P24F6?
Drive gently and only to a workshop. With P24F6 the car can go into limp mode (reduced power) to protect itself.
Will P24F6 fail an emissions test?
Yes, it can. P24F6 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P24F6 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P24F6 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.