Generic fault code
P20F1 — SCR NOx pre-catalyst: over temperature (bank 2)
The control unit stores code P20F1 when it detects this fault: “SCR NOx pre-catalyst: over temperature (bank 2)”.
Indicative severity: HighEmission control
Reviewed by Daniel Morales, founder of Reprorace SL, on
What does code P20F1 mean?
The catalytic converter, oxygen sensors, EGR, fuel vapor system (EVAP), particulate filter and NOx reduction clean the exhaust. A fault here raises pollution and may make the car fail its inspection; left alone, some end in a bigger fault or in limp-home mode.
- System
- P · Powertrain
- Area
- Emission control · Car system: Exhaust and emissions
- Type
- Generic (SAE J2012 / ISO 15031-6): the same meaning on every make
- Indicative severity
- High. Diagnose as soon as possible: it may affect safety or cause damage (engine, catalyst, brakes).
What usually causes code P20F1?
- Aftertreatment fault (catalyst, particulate filter, SCR, EGR)
The most likely causes come first. Only a check on the car confirms which one is yours.
What are the symptoms of code P20F1?
- AdBlue or emissions warning on the dashboard
- On many vehicles, a countdown in kilometres after which the engine will not restart
- Limp-home mode or limited power
These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.
Can I keep driving with code P20F1?
Better not, except when you really have to. This fault may affect safety or damage the engine, the catalytic converter or the brakes. See a workshop as soon as possible; if you must move the car, drive gently and only short distances. If the light flashes, the car loses power, makes unusual noises or the brakes or steering feel different, stop somewhere safe and call for assistance.
This is guidance only: only someone who checks the car can say whether it is safe to drive.
An indicative description of the code's generic meaning. Each manufacturer may give it a different meaning, conditions or tests: always follow its service information and your workshop's advice.
What you can do yourself
For this kind of fault
Check the AdBlue level and only use fluid that meets ISO 22241. If the warning stays with a full tank, do not wait for the countdown to end: book the workshop.
Read the code and keep the report: with an ECO-LITE in the OBD socket you see it on your phone or computer, with the data captured when the fault happened.
Look for anything obvious: a loose connector, a disconnected hose, a fuel cap not closed properly or a low fluid level. Do not take apart anything you do not know.
Clear the code only after writing it down or after the repair. Clearing turns the light off, but it also deletes the freeze-frame data and the readiness monitors used at the inspection.
Drive normally for a few days and read the codes again. If the code comes back, the fault is still there: book the workshop and bring the report.
Read your car's fault codes on your phone
With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.
Related codes
- P20E8Reductant pressure: too low
- P20EESCR NOx catalyst (bank 1, catalyst 1): efficiency below threshold
- P20F0SCR NOx catalyst: over temperature (bank 2)
- P20F2SCR NOx catalyst (bank 2): efficiency below threshold
- P20F3SCR NOx pre-catalyst (bank 2): efficiency below threshold
- P20F6Reductant injection valve (bank 1, unit 1): stuck open
P20xx codes: particulate filter, AdBlue and NOx
In the glossary
Read more: Remote OBD diagnostics: what it is, how it works and what it can't do