Volkswagen / Vehicle-specific diagnosis
VW Golf/Jetta TDI P0401: the DPF and EGR-filter repair
An EGR-flow fault needs a finding that explains the repair being proposed.
Check the vehicle first.
- Vehicles
- 2009 Jetta/Jetta Wagon CBEA; 2010–2014 Golf and Jetta variants CJAA; 2.0 TDI.
- Reviewed revision
- 2034898/23; this is a diesel-specific case.
The first branch is an actual soot finding
| Inspection at the EGR-filter/DPF connection | Bulletin direction |
|---|---|
| Black soot found inside the connection | Replace DPF and EGR filter together. |
| No soot found | Continue guided diagnosis; this repair branch does not apply. |
What the later airflow check changes
After repair, a correctly running, fault-free engine is tested at warm idle. Activated block 67, field 3 with EGR off selects smoke-testing at/above the specified threshold, or snow-flap/air-filter inspection below it.
Match the current guided-test units; arbitrary scanner values do not apply.
An estimate should explain additional exhaust parts
No automatic EGR-cooler, exhaust-flap or separate NOx/sulfur-catalyst replacement is prescribed. Assembly configuration affects necessary parts.
Resetting soot values belongs after replacement
Volkswagen’s separate TT 26-13-02 limits the ash/soot adaptation reset to a replaced DPF. Guided Functions performs the adaptation; the specified verification checks the reset values, completes service regeneration and rechecks faults and warning lamps.
The implication for an owner is straightforward: a reset record is evidence of a programming step, not evidence that a physical filter was replaced. Ask for both the repair record and the subsequent verification results. Do not use an adaptation reset to disguise a filter that is still fitted.
A useful workshop handover
Request a photo or written description of the inspection finding, identification of the installed exhaust assembly, and the reason for any extra component on the estimate. Ask which airflow branch applied and how the completed repair was verified.
These are editorial questions for checking that the invoice describes the work. Exhaust removal, pressurized testing and service regeneration belong in an equipped workshop; this article is not a procedure for removing or defeating emissions equipment.
Source documents
- 2034898/23 (2022-06-14)
Source reviewed .
- TT 26-13-02 (2013-10-04)
Source reviewed .