P20A6 code meaning
Reductant Injection Air Pressure Control Valve Circuit/Open
Powertrain system Generic code P20xx codes Check engine light
What P20A6 means
In an air-assisted DEF system the compressed air must reach the mixing point at a defined pressure, whether it comes from the vehicle's brake air supply or from a separate compressor. A solenoid valve sets or switches this air pressure. P20A6 marks an open circuit in its control: the controller commands the valve, but no current flows, so the atomizing air cannot be regulated. No manufacturer documents P20A6 publicly. Deutz, whose EMR L1 controller drives a similar air supply valve, files the open circuit under P2059 for the air pump or supply valve and under its own code P1062 for the air switching valve. Low and high faults of the same circuit are P20A8 and P20A9. Air-assisted dosing appeared with Bosch's Denoxtronic 1 in 2004 and was later replaced by airless systems.
P20A6 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P20A6
- SCR warning lamp or MIL on
- Dosing stops for lack of atomizing air
- Power derate on heavy vehicles
Common causes of P20A6
- Most likelySolenoid coil of the air pressure control valve open
- Most likelyConnector unplugged or wire broken near the valve
- PossibleFuse or supply feed for the valve missing
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant air pressure control valve
What each part of P20A6 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| A6 | The exact fault in that area. |
What to do next
- Note P20A6 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P20A6
What does P20A6 mean?
P20A6 means "Reductant Injection Air Pressure Control Valve Circuit/Open". In an air-assisted DEF system the compressed air must reach the mixing point at a defined pressure, whether it comes from the vehicle's brake air supply or from a separate compressor. It is a generic code, so it means the same on every make.
Is it safe to drive with P20A6?
Drive gently and only to a workshop. With P20A6 the car can go into limp mode (reduced power) to protect itself.
Will P20A6 fail an emissions test?
Yes, it can. P20A6 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P20A6 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P20A6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.