P204F: Reductant (AdBlue) system performance (bank 1)

What P204F means

The AdBlue system pumps fluid from its tank and sprays it into the exhaust through an injector so the SCR catalyst can remove nitrogen oxides. The ECU has found that the system is underperforming: it cannot reach the requested pressure or quantity, or the NOx sensors do not show the expected result.

Most common causes

• Low AdBlue level or poor quality AdBlue
• AdBlue injector blocked with urea crystals
• Worn AdBlue pump or blocked pump filter
• AdBlue lines blocked, kinked or leaking
• NOx sensor or AdBlue pressure sensor reading wrongly

Symptoms

• Engine warning light on
• AdBlue or emissions warning on the dashboard
• Possible countdown before the engine is prevented from starting
• White crystal deposits near the injector or exhaust

Can you drive with P204F?

With care You can drive, but get to a garage soon. On many cars, if the fault persists, a dashboard message counts down the distance left before the engine will not restart.

How to check it

First check the AdBlue level and top up if needed with fluid that meets ISO 22241. If you can see white crusty deposits around the injector on the exhaust, tell the garage: it points to a blocked or leaking injector.

How to read and clear P204F with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P204F with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• P2031 Exhaust gas temperature sensor circuit fault (bank 1, sensor 2)
• P2032 Exhaust gas temperature sensor circuit low (bank 1, sensor 2)
• P2033 Exhaust gas temperature sensor circuit high (bank 1, sensor 2)
• P2047 AdBlue injector circuit open or faulty (bank 1, unit 1)
• P207F Reductant (AdBlue) quality performance
• P2080 Exhaust gas temperature sensor reading out of range (bank 1, sensor 1)
• P2081 Exhaust gas temperature sensor circuit intermittent (bank 1, sensor 1)
• P2084 Exhaust gas temperature sensor reading out of range (bank 1, sensor 2)
• P2002 Diesel particulate filter efficiency below threshold (bank 1)
• P2003 Diesel particulate filter efficiency below threshold (bank 2)
• P2004 Intake manifold runner control stuck open (bank 1)
• P2005 Intake manifold runner control stuck open (bank 2)

P204F is a generic code, so it means the same on any make, for example on Abarth, Cupra, Jeep, Mini, Nissan, Seat. See what Final OBD does on your car in makes and models.