P0402 on Opel: How to Diagnose & Fix
Exhaust Gas Recirculation Flow Excessive
3 Opel models · 3 documented issues · 2 critical · $200-$1,800 repair
P0402 on Opel by model: symptoms, diagnosis and fix
The A17DTR/A17DTS 1.7 CDTI diesel in Astra J (2009-2015), Mokka A, and Meriva B suffers severe EGR valve carbon buildup, typically presenting between 80,000 and 150,000 km. Symptoms include power loss, limp mode, and rough idle. The EGR cooler can also crack, mixing coolant with intake flow.
Common Symptoms
- Loss of power
- Limp mode
- Rough idle
How to Fix
EGR valve clean or replacement (€400-€800 incl. labor). EGR delete is common but illegal in most markets and fails TÜV / MOT emissions tests. Walnut blasting helps the intake manifold simultaneously.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Vauxhall/Opel 97376663 / 95523829 EGR valve
Astra J 1.7 CDTI A17DTR/A17DTS among the seller's listed engine codes; verify VIN/engine code and whether adaptation is required.
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Sources for this issue (1)
Combo diesels (1.5 BlueHDi) used mainly for short, low-speed urban trips suffer from EGR valve carbon build-up and diesel particulate filter (DPF) blockage. The engine never reaches the temperature needed for passive/active DPF regeneration, so soot accumulates. A clogged DPF raises exhaust back-pressure, which alters EGR flow, while a sooty EGR increases soot output, creating a feedback loop that produces multiple emissions faults at once. Symptoms include rough idle, power loss, higher fuel use and limp mode. This is a well-known characteristic of the PSA/Stellantis diesels shared with the Berlingo/Rifter.
Common Symptoms
- DPF / engine warning light
- Limp mode / reduced power
- Rough idle and hesitation
- Increased fuel consumption
- Frequent or incomplete DPF regenerations
- Smell of unburnt diesel
How to Fix
Drive for at least 10-15 minutes at 65 km/h (~40 mph) or more regularly to allow the DPF to regenerate. Use the correct low-ash (low-SAPS) diesel oil. If already clogged, perform a forced regeneration via diagnostics, clean or replace the EGR valve, and clean or replace the DPF. Address any leaking injectors or weak turbo boost that overload the DPF with soot. Buyers doing only short trips should consider the petrol model instead of the diesel.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine 9829870080 five-pin EGR valve
Confirm VIN and five-pin OE 9829870080.
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Sources for this issue (1)
The A20DT/A20DTH 2.0 CDTI EGR cooler develops internal cracks, allowing coolant to leak into the intake. Symptoms: white smoke from exhaust, mysterious coolant loss with no external leak, sweet smell, eventual no-start as cylinders flood. Common at 100,000-180,000 km. Same engine in Astra J, Zafira C, Cascada.
Common Symptoms
- White smoke from the exhaust
- Coolant loss with no external leak
- Sweet smell
- Engine will not start
How to Fix
EGR cooler replacement €600-€1,200 incl. labor. If coolant has been pulled into cylinders, hydrolock check required. Some independents recommend EGR delete + remap — illegal in most markets and disqualifies TÜV inspection.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine 55590953/55572962 EGR cooler and valve repair kit
Insignia A 2009-2017 2.0 CDTi engine family listed as A20DT/A20DTC/A20DTE/A20DTH/A20DTJ/A20DTL/A20DTR and related Y/Z20 codes. Confirm VIN and OE 55590953/55572962.
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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 Opel?
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 Opel it is documented across 3 models: Astra, Combo, Insignia.
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 Opel?
Published repair estimates on Opel range from $200 to $1,800 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.