P20A5

Code

Generic P — Powertrain

Reductant Purge Control Valve A Stuck Closed

Brand: Generic

Type: P — Powertrain

Views: UK: 41 EN: 59 RU: 44

AI status

Completed

ready

Completed 100%

Page language: EN

Read freeze frame and full DTC report; check for related DEF/SCR codes
Check DEF tank level and verify no contamination or unusual odor
Visually inspect valve, wiring harness and connector for corrosion, damage, or loose pins
Listen for valve click when commanding purge with scan tool
Monitor live data: valve command vs actual feedback (if available) and pump pressure/flow
Measure coil resistance of the purge valve (compare to service spec)

Control type: typically a 12 V supply or PWM-driven solenoid (depends on vehicle)
Command signal: 0–100% duty cycle when PWM controlled; ‘on’ command should energize valve
Expected coil resistance: typically in the low ohm range (example 5–50 ohms depending on design) — consult OEM spec
Supply voltage at valve connector: battery voltage (approx. 11–14 V) when commanded
When commanded open, you should observe flow or a change in pressure/flow in the reductant circuit

Retrieve all related codes and freeze frame data; record live data for the reductant system.
Verify DEF level, inspect for contamination, and check for visible crystallization around tank, lines, and valve.
Visually inspect the valve connector and wiring for corrosion, bent pins, damaged insulation, or disconnected grounds.
With key on/engine off, measure valve coil resistance and compare to OEM specification. Replace if out of range or open.
Command the valve with a scan tool while monitoring voltage at the connector; confirm the ECM is sending the expected command and that supply/ground are present.
If ECM commands are present but valve does not operate, remove the valve and inspect internally for blockages or crystallized DEF. Clean or replace as required.
If valve functions when bench-tested but fails in-vehicle, trace wiring for intermittent opens/shorts, check connectors, and backprobe harness while actuating to find voltage drops.
Check upstream components: confirm DEF pump operation and line pressure/flow to the purge valve and inspect the purge/nozzle for clogs.
If wiring and valve check good but no control signal from ECM, test ECM output driver and grounds per OEM procedures; consider reprogramming or replacement if confirmed defective.
After repair or part replacement, clear codes and perform a drive or regeneration cycle and recheck system operation and for return of the code.