P20A0 code meaning
Reductant Purge Control Valve A Circuit/Open
Powertrain system Generic code P20xx codes Check engine light
What P20A0 means
After the engine stops, many airless DEF systems suck the fluid out of the line and injector back into the tank so that nothing freezes there. In Bosch's Denoxtronic 2.2 this is done by a 4/2-way valve in the supply module that reverses the flow. P20A0 concerns the drive circuit of this valve, chiefly an interruption. GM checks it on the 6.6 L Duramax (LML/LGH) with the driver switched off: an impedance above 200 kΩ between ECM pin and load for 3 s sets the code, Type A. Volkswagen, on the 2014 Touareg 3.0 TDI (CNRB), uses a power-stage voltage between 2.97 and 4.70 V. Shorts to ground and to power are split off as P20A2 and P20A3. If the line cannot be emptied, DEF may stay in the injector and line and freeze there in winter.
P20A0 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P20A0
- MIL on (GM Type A, first trip)
- DEF system or emission service message
- Risk of frozen DEF line or injector in winter
Common causes of P20A0
- Most likelyCoil of the purge or reversing valve open
- Most likelyConnector at the supply module loose or corroded by DEF
- PossibleWire to the valve broken
- Less likelyOutput stage in the engine or dosing control unit defective
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant purge valve
What each part of P20A0 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. |
| A0 | The exact fault in that area. |
What to do next
- Note P20A0 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 P20A0
What does P20A0 mean?
P20A0 means "Reductant Purge Control Valve A Circuit/Open". After the engine stops, many airless DEF systems suck the fluid out of the line and injector back into the tank so that nothing freezes there. It is a generic code, so it means the same on every make.
Is it safe to drive with P20A0?
Drive gently and only to a workshop. With P20A0 the car can go into limp mode (reduced power) to protect itself.
Will P20A0 fail an emissions test?
Yes, it can. P20A0 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 P20A0 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P20A0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.