P20EAReductant Control Module Power Relay De-Energized Performance - Too Early
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Many SCR systems supply the reductant control module, and through it pump and heaters, via a power relay. After the key is switched off the relay should stay energised for a short after-run so the pump can empty the lines and the module can save its learned values, and only then drop out on the module's command. P20EA means the supply disappeared before that point. Fluid left in the lines can then freeze or crystallise, and stored data may be lost. No maker documents P20EA publicly. The monitoring follows the engine-module pair P068A/P068B: Saab's 2011 9-5 diesel reads back the relay voltage on its control line, and Ford's 2023 diesel summary checks the reductant control module relay (P21C7) by comparing commanded state with the measured voltage. A relay that drops out late is P20EB.
- What you may notice
- Check engine light, often without noticeable driving symptoms
- DEF lines not purged, risk of frozen or crystallised lines in winter
- Likely causes
- LikelyWorn relay contacts or coil interrupting the supply early
- PossibleLoose fuse, terminal or ground in the relay or module feed
- PossibleBattery disconnected or voltage collapsing right after shut-off
- RareReductant control module releasing the relay prematurely
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.