06/10/2026
FLASHING DPF LIGHT… BUT THE DPF WASN’T THE REAL PROBLEM!
Friday night we towed this 2019 Mitsubishi Triton towed into the workshop with a flashing DPF light on the dash.
First priority? We sorted the customer out with a loan car so they could get back to Bundaberg while we got to work finding out what was going on.
The Triton still drove reasonably well and, with only 120,000km on the clock and not overdue for a service, you wouldn’t necessarily expect what we found next…
The engine oil level was massively overfull.
That’s a big warning sign.
Repeated unsuccessful DPF regenerations can result in diesel fuel contaminating the engine oil — so rather than simply forcing another DPF burn and sending it on its way, we wanted to find out WHY the DPF wasn’t regenerating properly.
We smoke-tested the intake system and found the culprit:
A pinhole leak in a boost/charge pipe.
Small fault. Big flow-on effect.
That boost leak was affecting the conditions the engine needed for the DPF system to operate correctly — and it’s a great example of why replacing or cleaning a DPF without properly diagnosing the vehicle can be an expensive mistake.
The fix:
New charge pipe
Intake clean
Fresh engine oil & filter to remove the fuel-diluted oil
Confirm correct DPF operation
Final checks before handing it back
And this Triton is back on the road!
Modern DPF systems are generally pretty reliable. When one starts giving trouble, there’s often an underlying reason — the important part is finding it.
If your diesel has a DPF warning light, is carrying out frequent burns, has rising engine oil levels or just isn’t behaving like it normally does, don’t ignore it.
Diagnose the cause — don’t just treat the warning light.
