P0402 on Volkswagen: How to Diagnose & Fix
Exhaust Gas Recirculation Flow Excessive
2 Volkswagen models · 2 documented issues · $200-$1,500 repair
P0402 on Volkswagen by model: symptoms, diagnosis and fix
Independent of the Dieselgate recall, the Caddy TDI's EGR system clogs with soot/carbon over time. The valve sticks or the EGR passages clog with carbon, triggering 'insufficient flow' (P0401) or 'excessive flow' (P0402) codes. The van may otherwise run normally or may drop into limp mode with reduced power. EGR replacement at a VW dealer is costly and a post-repair ECU software update is required.
Common Symptoms
- Limp mode / reduced power
- Engine warning light
- Rough running
- Hesitation under load
How to Fix
Read codes; clean the EGR valve and intake passages (often an inexpensive fix for P0401). If the valve itself is faulty it must be replaced and the ECU re-flashed. Regular motorway runs and quality fuel slow carbon build-up.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (2)
The 2.0 TDI's diesel particulate filter blocks up on cars used mainly for short, low-speed urban journeys, because the engine never reaches the sustained temperatures needed for passive/active regeneration. A clogged DPF (often combined with a sooty or sticking EGR valve) triggers the exhaust/glow-plug warning lamp, reduced power, limp mode, heavy smoke and more frequent forced regenerations. Reports note this worsened on some cars after the dieselgate NOx emissions software update, which increased regeneration frequency, rough idle and DPF warnings.
Common Symptoms
- Glow-plug/exhaust warning light flashing
- Reduced power / limp mode
- Frequent regenerations / smell of burning
- Black smoke from exhaust
- Higher fuel consumption
- Rough idle after emissions update
How to Fix
Confirm with diagnostics. A partially blocked DPF can sometimes be cleared with a high-speed regeneration run or a forced regen via VAG tooling; a heavily clogged filter needs professional off-car cleaning or replacement, and the EGR valve may need cleaning/replacement. Regular longer/faster drives and correct LongLife diesel oil reduce recurrence. (DPF removal/delete is illegal for road use in the UK/EU and fails the MOT/TÜV.)
Sources for this issue (2)
P0402 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0402 mean on a Volkswagen?
P0402 stands for "Exhaust Gas Recirculation Flow Excessive." P0402 means the Exhaust Gas Recirculation (EGR) system is flowing too much exhaust back into the intake. The EGR system intentionally routes a small amount of inert exhaust gas into the engine to lower combustion temperatures and reduce nitrogen-oxide emissions, but the flow must be metered precisely. When the PCM determines the flow is excessive — often because the EGR valve is stuck open or letting gas through when it shouldn't — it sets this code. Too much EGR can cause rough idle, stalling, hesitation, and a check engine light. On Volkswagen it is documented across 2 models: Caddy, Scirocco.
What are the most common causes of P0402?
The most common causes of P0402 are: EGR valve stuck open or not closing fully, Failed or sticking EGR valve diaphragm/solenoid, Carbon buildup holding the EGR valve open, Faulty EGR position or differential pressure (DPFE) sensor, Leaking EGR valve gasket or pintle seat, Vacuum control or solenoid fault commanding EGR open, Wiring or connector problems in the EGR control circuit. The specific cause varies by vehicle.
How much does it cost to fix P0402 on a Volkswagen?
Published repair estimates on Volkswagen range from $200 to $1,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.