DS Citroën DS5 DPF Fix for P2463 and P246C: Why the Light Kept Coming Back

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Citroën DS5 DPF Fix for P2463 and P246C: Why the Light Kept Coming Back

A 2015 Citroën DS5 came into O'Rileys Autos with the engine management light and the service light on, showing 104,000 miles. On the dash, the car also warned of a risk of particle filter clogging.

The owner's problem sounded familiar: the DPF had been "cleaned" more than once, yet the warning returned after about 50 miles. When that happens, the real fault often sits behind the symptoms, so the first job was to stop guessing and start measuring.

The repeat DPF blockage that wouldn't stay fixed

Two different DPF cleaners had already visited. Each time, fluid went in, the car drove fine briefly, then the DPF message returned. One cleaner said the filter was clean but couldn't explain why the fault came back. Another suggested a motorway run, but that still didn't solve it.

When you're stuck in that loop, it feels like you're "going around in circles", because the light resets but the cause stays put.

At this point, the key question wasn't "can it regen?", it was "why is the pressure still high after a regen?"

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Diagnostics started with the Kingbolan K8 Pro using intelligent diagnose, which correctly identified the car as a DS5 (2015). With the warning still present, fault codes and live data were the next step.

Here's what stood out first.
Live data then showed the additive (PAT fluid) estimated at about half a litre, although that can be optimistic.

Live data that pointed to ash, not soot

The exhaust data told the real story. Distance between regens showed 200 km, which is long. However, it also showed a regen had happened about 60 km ago. Despite that, differential pressure sat around 34 mbar, which is high for a filter that has recently regenerated.

That combination matters because regen burns soot. It doesn't remove ash.

Jimmy's call was clear: either the DPF was damaged (for example, melted), or it had hard ash build-up, the stubborn, gritty stuff that won't shift with an on-car flush.

Removing the DPF and cleaning it properly off the car

With the DS5 on ramps, the DPF came off for inspection and machine cleaning. The rear end looked clean, which was a good sign, but there was a weld on the exhaust joint from a previous removal, so that had to be cut.

The DPF then went onto a Carbon Clean DCS16 machine, which uses air pressure, water, and cleaning solution. Almost straight away, red, sandy ash poured out.

1. Mount the DPF to the machine
2. Pump pressure, then blast through
3. Repeat until the fluid runs clear

That red ash is the giveaway. It won't properly clear while the DPF stays on the car.

Refitting, programming, PAT fluid, and the pressure drop

After refitting, fault codes were cleared, then the engine was run and revved to help dry the wet DPF. At around 3,000 rpm, pressure started near 70 mbar and steadily fell. Once idling, it settled at about 4 mbar, right in the desired 1 to 6 mbar range.

Steam from the exhaust was expected because the DPF was drying, not smoking.

Meanwhile, Brian filled the PAT fluid tank (the car had been owned from new and never filled at 104,000 miles) and the fill was programmed in via the diagnostic menu (draining/filling, additive reservoir). Finally, a short 4 to 5-mile test drive confirmed no warning lights returned.

Conclusion

This DS5 didn't fail because it couldn't regenerate, it failed because regen couldn't remove the ash blocking the system. Once the DPF came off for a proper reverse clean, pressures dropped back to normal, the PAT fluid was topped up and programmed, and the car left ready for the road. If a DPF light returns again and again after "cleaning", the live data usually tells you why.
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