P0402 on Audi
Exhaust Gas Recirculation Flow Excessive
P0402 on Audi vehicles indicates exhaust gas recirculation flow excessive. Au7o has documented this code across 1 Audi model — most commonly on A1. 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. Typical repair costs on Audi range from $200 to $1,500, depending on the specific model and root cause.
Common Causes of P0402
- •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
P0402 on Audi by Model
Audi A1(1 issue)
- 1.6 / 2.0 TDI Diesel DPF Clogging and EGR Valve Faults2010-2018
The A1 is sold mainly as a town/city car, so diesel (1.6 TDI / 2.0 TDI) owners doing short, stop-start journeys never get the diesel particulate filter hot enough for passive regeneration. The DPF clogs with soot, and a faulty/sticking EGR valve accelerates this by raising soot output. Failed active regens can also dilute the engine oil with diesel. A blocked DPF triggers limp mode and is expensive to replace.
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View P0402 across all makes →Frequently Asked Questions
What does P0402 mean on Audi?▼
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 Audi specifically, this code is documented across 1 model.
What causes P0402 on Audi vehicles?▼
Common causes on Audi: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0402 on a Audi?▼
Repair costs on Audi range from $200 to $1,500, depending on the specific model and root cause.
Which Audi models have P0402 documented?▼
Au7o has documented P0402 on 1 Audi model: A1.