OBD-II code · Powertrain (generic, extended)
P20F3 SCR NOx Pre-Catalyst Efficiency Below Threshold (Bank 2)
SCR NOx Pre-Catalyst Efficiency Below Threshold (Bank 2): the control module has detected this fault condition.
Is it safe to drive with P20F3?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyPre-catalyst thermally aged
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–8 h
- Emissions test
- Likely to fail
- Parts involved
- Scr Pre Catalyst
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.