P20E6Reductant Injection Air Pressure Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- This code belongs to air-assisted DEF dosing, where compressed air carries the fluid to the nozzle and breaks it into fine droplets; airless pump systems in cars and most current pickups do not use it. P20E6 means the air pressure in the dosing branch stays below the minimum the control unit needs while dosing is requested. A Cummins patent for such a system gives an example limit: if the combined air and DEF pressure remains under about 300 kPa for 10 s, a low-pressure fault is stored, pointing to a weak air supply or compressor, a shut-off valve that does not open, blocked or leaking lines, or crystallised DEF blocking the air path. Cummins bulletin TSB200096 describes crystal build-up on the air side of such dosing units that cuts air flow. No maker documents P20E6 itself publicly. Leakage is P20CA, excess pressure P20E7.
- What you may notice
- Check engine light and SCR warning
- DEF dosing reduced or stopped, rising NOx emissions
- Engine derate after the inducement period
- Likely causes
- LikelyInsufficient air tank pressure from a leak or weak compressor
- PossibleAir shut-off or pressure control valve not opening
- PossibleDEF crystals restricting the air side of the dosing unit
- PossibleLeaking, kinked or blocked air line to the doser
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.