P20F2SCR NOx Catalyst Efficiency Below Threshold (Bank 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P20F2 is the bank 2 twin of P20EE: the main SCR catalyst of the second exhaust line removes less NOx than required, judged by NOx sensors ahead of and behind it. CARB requires the NOx catalyst to be flagged once its conversion loss would push emissions past the regulatory multiple of the standard. No manufacturer documents P20F2 publicly; the widely used P20EE logic shows how such a monitor works. Ford's 2023 6.7 L diesel, for example, fails its catalyst below 55 % cumulative efficiency within a 200–320 °C inlet window, and GM compares measured with expected efficiency. A bank 2 code requires a dedicated SCR and sensor pair per bank. If both banks report low efficiency together, DEF quality or a shared supply fault is more likely than two worn catalysts. A speed limit may follow where the vehicle treats it as a DEF fault.
- What you may notice
- Malfunction indicator lamp on
- DEF quality warning, possibly with a countdown to reduced speed
- Likely causes
- LikelyPoor DEF quality or bank 2 dosing valve fault
- LikelyBank 2 NOx sensor reading wrong
- PossibleBank 2 SCR catalyst aged or overheated
- RareExhaust leak between the bank 2 NOx sensors
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €4,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.