P2002 — DPF Efficiency Below Threshold (GWM Context)
Standard meaning: the differential-pressure sensor says the diesel particulate filter isn’t trapping soot at the efficiency the ECU expects. On a GWM Cannon, P2002 is the code form of the pattern we document on the problems page: a work ute living on short suburban trips that never let a regeneration cycle finish. The filter is usually fine; the duty cycle isn’t.
What it means on your GWM
| If you drive… | The documented pattern | First move |
|---|---|---|
| Cannon diesel, mostly urban | Regens keep aborting mid-cycle; soot load climbs; efficiency reading falls. | A 30–40 minute uninterrupted highway run at steady speed, then see if the light clears after a drive cycle. |
| Cannon diesel, highway ute | Duty cycle is right, so the sensor story matters more: differential-pressure sensor or its hoses can misread. | Workshop check of the DP sensor and lines before any talk of filter replacement. |
| Any diesel, after remap/deletes | Out of our scope and usually illegal on-road in Australia. | — |
Safe owner checks — before any parts are bought
- Honest duty-cycle audit: when did this ute last run 30+ minutes without stopping?
- Any recent short-trip streak, then the light? That’s the pattern, not a failure.
- Oil level rising or smelling of diesel? Failed regens dilute oil — that’s a workshop visit, not a highway run.
When it’s a workshop job
If a proper highway cycle doesn’t clear it, if the code returns within days, or if power loss/limp mode arrives with it — the workshop needs to read soot load and command a forced regeneration, and to rule out the pressure sensor. A genuinely full filter after repeated ignored warnings is an expensive part; the habit that prevents it is free. Budget for the habit.
Code definition per SAE J2012. Pattern evidence: our Cannon problems research (cross-verified DPF pattern, AU owner and specialist documentation).