P20A2 code meaning
Reductant Purge Control Valve A Circuit Low
Powertrain system Generic code P20xx codes Check engine light
What P20A2 means
The purge valve that reverses the DEF flow at shutdown is usually switched on the ground side. P20A2 reports that its control line is pulled too low, typically a short to ground somewhere between the driver and the coil, which would switch the valve on unintentionally or keep the driver from sensing it. GM tests the low-side driver of the 6.6 L Duramax with the output off and sets P20A2 when the impedance to controller ground is under 0.5 Ω for 2 s, Type A. Volkswagen flags the Touareg 3.0 TDI (CNRB, 2014) when the power-stage voltage falls below 2.97 V. Compared with P20A0, where the line is open, the fault here is an unwanted connection to ground. Chafed wiring near the tank and water in the connector are the usual findings; the controller may then block dosing.
P20A2 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 P20A2
- MIL on at once (GM Type A)
- Service emission or DEF system message
- Dosing possibly disabled
Common causes of P20A2
- Most likelyControl wire chafed against the frame or tank bracket
- PossibleMoisture or DEF in the valve connector creating a leakage path
- Less likelyValve coil shorted to its housing
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 P20A2 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. |
| A2 | The exact fault in that area. |
What to do next
- Note P20A2 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 P20A2
What does P20A2 mean?
P20A2 means "Reductant Purge Control Valve A Circuit Low". The purge valve that reverses the DEF flow at shutdown is usually switched on the ground side. It is a generic code, so it means the same on every make.
Is it safe to drive with P20A2?
Drive gently and only to a workshop. With P20A2 the car can go into limp mode (reduced power) to protect itself.
Will P20A2 fail an emissions test?
Yes, it can. P20A2 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 P20A2 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P20A2 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.