P0402: Exhaust Gas Recirculation Flow Excessive Detected
Moderate SeveritySafe to drive (short-term)Emissions
P0402 means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
Estimated repair costFrom €68 to €1400+, varies by vehicle
What does P0402 mean?
P0402 means the EGR system is flowing too much exhaust gas back into the intake manifold. The most common cause is an EGR valve stuck partially open, often due to carbon buildup on the valve seat. Diesel engines are especially vulnerable because of higher soot output.
P0402 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0402 and illuminates the check engine light.
What are the symptoms of P0402?
If your vehicle has triggered P0402, you may notice one or more of these symptoms:
Check engine light illuminated
Rough or unstable idle, sometimes stalling at stops
Hesitation or stumble during light acceleration
Black smoke from exhaust under load (diesel)
Reduced fuel economy and slight loss of power
What causes P0402?
Here are the most common causes of P0402, ranked by how likely they are to be the culprit:
highEGR valve stuck partially open from carbon buildup on valve seat
highFailed EGR valve solenoid or motor not closing fully
mediumClogged or sticking EGR position sensor giving false readings
mediumDamaged EGR valve diaphragm or vacuum hose leak (vacuum-operated systems)
lowFaulty MAP or DPFE sensor causing incorrect flow calculation
Is it safe to drive with P0402?
Generally yes, for short-term driving. Driveable short-term, but excessive EGR flow causes rough idle, hesitation, and may stall the engine at low RPM. Extended driving with excess EGR contaminates the intake and accelerates carbon buildup on intake valves (especially direct-injection engines). Get it fixed before next emissions test.
How do you diagnose P0402?
Follow these steps to pinpoint the root cause of P0402:
Read freeze frame data and check whether the fault appears at idle, cruise, or under load
Remove the EGR valve and inspect the seat and pintle for carbon buildup preventing full closure
Command the EGR valve closed with a scan tool and verify it seats fully (position sensor should read 0%)
Inspect vacuum hoses (vacuum-operated systems) for leaks that hold the valve cracked open
On diesel engines, inspect the EGR cooler for internal damage and verify the MAP sensor reads correctly against a known-good reference
How much does P0402 cost to fix?
Repair costs for P0402 vary depending on the root cause and your vehicle. Here are typical estimates:
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean EGR valve and passages
€8–€25
€60–€180
€68–€205
Moderate
Replace EGR valve (petrol or diesel)
€150–€450
€80–€220
€230–€670
Moderate
Replace EGR cooler assembly (diesel)
€300–€800
€250–€600
€550–€1400
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0402 on specific vehicles
P0402 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
P0402 on BMW 3 Series
BMW 3 Series • 2007–2024
The 320d with N47 and later B47 engines is notorious for EGR-related faults. Carbon buildup at the EGR valve seat is virtually guaranteed past 120,000 km, and the EGR cooler often cracks internally, leaking coolant into the exhaust stream. When P0402 appears alongside P0401 or low-coolant warnings, suspect cooler failure. BMW issued recall campaigns in several EU markets for N47/B47 EGR cooler fires.
What causes P0402 on a BMW 3 Series?
BMW 3 SeriesN47/B47 EGR valve seat carbon buildup preventing full closure
BMW 3 SeriesEGR cooler internal crack causing coolant intrusion and stuck-open valve
P0402 repair cost for BMW 3 Series
Estimated costs for BMW 3 Series ownersadjusted higher than average due to BMW-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean EGR valve and passages
€11–€35
€84–€252
€95–€287
Moderate
Replace EGR valve (petrol or diesel)
€210–€630
€112–€308
€322–€938
Moderate
Replace EGR cooler assembly (diesel)
€420–€1120
€350–€840
€770–€1960
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0402 on Volkswagen Golf
Volkswagen Golf • 2009–2024
Golf TDI models with the EA189 (pre-Dieselgate) and EA288 (post-fix) engines commonly throw P0402 after the emissions software update was applied. The remapped EGR strategy runs the valve at higher duty cycles, which accelerates carbon buildup at the seat. Cleaning the valve and intake manifold passages restores normal operation. On 1.4 TSI petrol Golfs, the integrated EGR cooler in the exhaust manifold can also stick open.
Volkswagen GolfEA288 intake manifold runners clogged from heavy EGR duty cycle
P0402 repair cost for Volkswagen Golf
Estimated costs for Volkswagen Golf ownersadjusted higher than average due to Volkswagen-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean EGR valve and passages
€9–€29
€69–€207
€78–€236
Moderate
Replace EGR valve (petrol or diesel)
€173–€518
€92–€253
€265–€770
Moderate
Replace EGR cooler assembly (diesel)
€345–€920
€288–€690
€633–€1610
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0402 on Audi A4
Audi A4 • 2008–2024
The A4 2.0 TDI (B8 and B9 chassis) shares EA189 and EA288 engines with the Golf and suffers identical EGR carbon issues. The valve is harder to access on the A4 due to tighter engine bay packaging, which pushes labor costs higher. On 3.0 TDI V6 models, the dual EGR coolers add complexity and parts cost when failure occurs.
What causes P0402 on a Audi A4?
Audi A4EA189/EA288 carbon buildup with tighter engine bay access on B8/B9
Audi A43.0 TDI V6 dual EGR cooler assembly failure (higher parts cost)
P0402 repair cost for Audi A4
Estimated costs for Audi A4 ownersadjusted higher than average due to Audi-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean EGR valve and passages
€10–€31
€75–€225
€85–€256
Moderate
Replace EGR valve (petrol or diesel)
€188–€563
€100–€275
€288–€838
Moderate
Replace EGR cooler assembly (diesel)
€375–€1000
€313–€750
€688–€1750
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0402 on Mercedes Sprinter
Mercedes Sprinter • 2010–2024
Sprinter vans with the OM651 2.1 CDI engine are heavy commercial users that see EGR faults early due to high duty cycles and frequent low-load city driving. The EGR cooler interacts with the AdBlue (SCR) system, so a stuck-open EGR valve often pulls down NOx sensor readings and triggers AdBlue limp-mode countdown. Cleaning is rarely a long-term fix on commercial Sprinters, replacement is more common.
What causes P0402 on a Mercedes Sprinter?
Mercedes SprinterOM651 EGR valve carbon buildup amplified by low-load commercial use
Mercedes SprinterAdBlue/SCR system limp-mode countdown triggered by stuck-open valve
P0402 repair cost for Mercedes Sprinter
Estimated costs for Mercedes Sprinter ownersadjusted higher than average due to Mercedes-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean EGR valve and passages
€10–€33
€78–€234
€88–€267
Moderate
Replace EGR valve (petrol or diesel)
€195–€585
€104–€286
€299–€871
Moderate
Replace EGR cooler assembly (diesel)
€390–€1040
€325–€780
€715–€1820
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Related diagnostic codes
These codes are often seen alongside P0402 or indicate related issues:
Short distances yes, but expect rough idle and possible stalling. Excessive EGR flow dumps soot and exhaust into the intake, which accelerates carbon buildup on intake valves, especially on direct-injection engines. Get it diagnosed within a few weeks.
Is EGR delete legal in the EU?
No. EGR delete is illegal across the EU and UK. It increases NOx emissions, triggers a permanent check engine light, fails the periodic technical inspection (TÜV in Germany, ITV in Spain, TA in Lithuania, SKP in Poland), and can result in vehicle deregistration. Stick to cleaning or replacement.
Will cleaning the EGR valve fix P0402?
Often yes. P0402 is usually caused by carbon stopping the valve from closing fully. Removing the valve, soaking it in EGR cleaner or carb cleaner, and clearing the seat resolves the code on roughly half of cases. If the solenoid or motor itself has failed, replacement is needed.
Why does my diesel keep throwing P0402 after cleaning?
Diesel engines produce far more soot than petrol, so the EGR valve re-fouls quickly. If the EGR cooler is also blocked or leaking internally, the valve will stick open again within months. On heavily affected engines (BMW N47, M57), the cooler often needs replacement alongside the valve.
