OBD-II code · Powertrain (generic, extended)
P20F7 Reductant Injection Valve Stuck Open (Bank 2 Unit 1)
The DEF injection valve at bank 2 unit 1 does not close when commanded — DEF flows continuously into the SCR. Risk of crystallisation in the catalyst and over-dosing.
Is it safe to drive with P20F7?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyValve seat eroded or contaminated
- Less likelyCarbon or debris buildup preventing free movement
- Less likelyComponent wear with age - mechanical play
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Injection Valve
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.