Ford Transit Custom 2.2 P26A1 DPF Fault: Why Repeated Cleaning Didn't Fix It

Ford Transit Custom DPF Fault: Why Repeated Cleaning Didn't Fix It A Ford Transit Custom DPF fault kept coming back, even after the filter had been cleaned several times elsewhere. The van arrived with the engine management light on, 122,000 miles on the clock, and a familiar story, clean the DPF, send it out, then see the light return a few days later. This case showed why that approach fails. The DPF was blocked, but the bigger issue sat in the exhaust after-treatment system, so cleaning alone was never going to last. The problem wasn't just a blocked DPF A scan with a KingBolen K8 Pro quickly changed the direction of the job. available here... 5% Off Kingbolen K8 Pro all system scan tool Lifetime free update Discount code YZHKNH36 End 2026-3-16 https://www.amazon.co.uk/dp/B0FL73NZZZ Yes, the DPF showed as blocked, but one fault mattered more than anything else, P26A1, which points to the exhaust after-treatment glow plug, also known here as the vaporiser. On many vehicles, glow plug faults can stop regeneration. On this Transit, the standard engine glow plugs were logged too, but they were not the reason the DPF fault kept returning. The key problem was the vaporiser circuit. If the vaporiser fault stays in place, cleaning the DPF is just a short-term patch. The live data backed that up straight away. These readings told the real story: DPF load 172% Idle pressure 37.8 mbar ideal idle pressure is between 1 to 6 mbar Pressure at 2500 rpm 180 to 190 mbar. ideal 2500rpm pressure 30 to 50 mbar So, the DPF was heavily restricted. Still, there was no point forcing more regens or cleaning it again without fixing the fault that stopped proper regeneration in the first place. Inspection under the van revealed the missing piece Once underneath, the vaporiser looked untouched. The unit and fixings were rusty, which strongly suggested no one had removed or replaced it before. The original plan was to remove the DPF fully, inspect it for damage, and clean it properly. However, the turbo-side bolts were extremely tight, and snapping them would have meant a much bigger job. Because of that risk, the repair stayed on-vehicle. The team checked the vaporiser circuit and found a blown yellow fuse for the vaporiser. That mattered because a new vaporiser can still appear faulty if the old blown fuse is left in place. A genuine Ford vaporiser was fitted, then DPF cleaning fluid was fed into the filter through the pipework. After that, the scan tool was used to: 1. Reset the DPF values to 0% 2. Prime the vaporiser 3. Clear the relevant faults The pressure drop showed the repair was working With the van running at roughly 2500 rpm, steam started coming from the exhaust as the cleaner worked through the system. Pressure dropped from around 180 mbar to 50 mbar, then settled at 7 to 8 mbar at idle, which is acceptable for a Transit. To prove the repair, a short regen was triggered for about five minutes. That was not done to fully regenerate the DPF. It was simply a safe test to confirm the vaporiser now operated correctly, without short-circuit faults or another blown fuse. After the check, only the standard glow plug faults remained. Those were already known, and earlier notes showed attempts to remove some had risked snapping them, so they were left alone for now. The result The van then went out for a road test while live data was monitored. DPF pressure stayed low, the system remained stable, and the engine management light stayed off. The big lesson here is simple. Recurring DPF faults are not always fixed by another clean. When a Transit Custom has a vaporiser fault staring back in the fault codes, that needs sorting first, or the same problem will keep coming back.