EGR flow insufficient on Peugeot 1.6/2.0 HDi (PSA DV6/DW10) diesels — sticking EGR valve or clogged FAP/DPF causing back-pressure.
Peugeot P0401 — EGR flow insufficient on Peugeot 1.6/2.0 HDi (PSA DV6/DW10) diesels — sticking EGR valve or clogged FAP/DPF causing back-pressure. Typical UK independent garage cost: £180–£720.
What actually causes P0401 on a Peugeot
The PSA DV6 1.6 HDi (also in Ford Focus/Fiesta/C-Max as TDCi, in Mini D, and Volvo D2) is one of the most P0401-prone engines on UK roads. EGR valve sticks half-open, FAP (PSA's DPF with Eolys additive) clogs early on town cars, and additive runs out unnoticed. On 2.0 HDi the EGR valve itself is more robust but the cooler chokes up.
Peugeot engines that log P0401
- 1.6 HDi DV6 (208, 308, 3008, Partner, 5008)
- 2.0 HDi DW10 (407, 508, 3008, 5008, Expert)
- 1.4 HDi DV4 (107, 207, 1007)
How we diagnose P0401 on a Peugeot
- Lexia / Diagbox — read EGR position feedback and Eolys fluid level
- Inspect EGR valve for carbon — clean or replace
- Check FAP differential pressure and soot loading percentage
- Top up Eolys additive if below 1 litre
- Force a regen and re-test
The common misdiagnosis to avoid
Don't replace the EGR valve before checking the Eolys (FAP additive) level on PSA diesels — empty Eolys tank causes the FAP to clog, raises back-pressure, and triggers P0401. Refill is £40 of fluid.
Peugeot P0401 repair cost in the UK
Expect £180–£720 including parts and labour at an independent garage. Main-dealer quotes on Peugeot are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
If a customer brings you a 1.6 HDi with P0401 and 'mostly does school runs', be honest with them — clean the EGR and FAP this time, but explain that without longer runs at proper temperature, you'll see them again in 12 months. Some customers will switch back to petrol on that advice.
Codes usually seen alongside P0401 on Peugeot
- P2002
- P1435
- P1340
Symptoms drivers report with P0401
- Engine management light on with no drivability change day-to-day
- Slight power loss and 1–3 mpg drop over the last few thousand miles
- Rough idle when hot, especially after motorway driving followed by traffic
- Occasional puff of black smoke on hard acceleration from cold
- EGR valve rattle / buzz when key is first turned (stepper motor testing itself against carbon)
- MOT emissions test borderline or fails on smoke opacity
- Paired codes: P0402 (EGR excessive flow), P0403 (EGR circuit), P2463 (DPF soot high — blocked EGR overloads DPF), P042E (EGR stuck open)
Repairs that clear P0401
- EGR valve clean or replacement
- Carbon-clean intake manifold
- Replace EGR sensor
- Diesel: check DPF condition
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0401 guide.