EGR system flowing too much exhaust gas.
P0402 — also written PO4O2, P 0402, 0402 — is the OBD-II code for egr flow excessive. Same code, same fix: this page covers every spelling of it.
EGR flow excessive — opposite of P0401. Usually a stuck-open EGR valve or a fouled DPF differential pressure sensor reporting wrong values.
P0402 is a emissions fault code, typically costing £150–£700 to put right in a UK garage.
What P0402 actually feels like to drive
- Rough idle, often shaking the gear lever
- Hesitation off the line
- Stalling at junctions
- Possible black smoke at idle
- Engine warning light + power reduction warning
What causes P0402?
- Stuck-open EGR valve
- Carbon-blocked seat
- EGR sensor fault
UK vehicles that throw P0402 most often
- Ford Focus / Mondeo 2.0 TDCi
- Vauxhall Astra / Zafira 1.7 / 2.0 CDTi
- VW Golf / Audi A3 2.0 TDI
- BMW 320d N47 / B47
- Citroën / Peugeot 1.6 / 2.0 HDi
How P0402 is fixed
- EGR clean or replace
- Sensor inspection
The P0402 misdiagnosis that wastes money
If a P0402 is logged alongside a DPF code, always check the differential pressure sensor and its pipes before blaming the EGR — blocked sensor pipes give false EGR flow readings.
What a UK garage should charge for P0402
EGR clean £90–£180, EGR valve replacement £260–£620 fitted, differential pressure sensor £40–£100, pipe replacement £25–£60.
P0402 repair cost in the UK
Most P0402 repairs land between £150–£700 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0402
Tap the EGR valve gently with a screwdriver handle while the engine is running and the symptoms are present — if the idle changes, the valve is mechanically sticky and replacement is the right call.
Can you drive with P0402?
Drivable.
Urgency: medium.