Reductant Control Module Power Relay De-Energized Too Early
The P20EA code indicates that the powertrain control module (PCM) detected the reductant control module power relay de-energizing earlier than expected. This relay supplies power to the reductant control module, which manages the diesel exhaust fluid (DEF) system. Early de-energization can disrupt DEF injection, leading to increased emissions and potential derate of engine power. Common causes include a faulty relay, wiring issues, or a failing reductant control module.
01. Most Common Causes
- Faulty reductant control module power relay
- Corroded or damaged wiring/connectors in the relay circuit
- Failed reductant control module
- PCM software or hardware issue
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power (derate)
- Increased diesel exhaust fluid consumption
- Possible no-start or hard start
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Inspect the reductant control module power relay and its circuit for damage, corrosion, or loose connections.
Step 3: Test relay operation using a multimeter; replace if faulty.
Step 4: Check voltage and ground at the reductant control module; repair wiring as needed.
Step 5: If all else is fine, replace the reductant control module.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the vehicle may enter a derate mode, reducing power and potentially causing further emissions issues. Immediate diagnosis is advised.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a relay replacement, but could be higher if the reductant control module needs replacement (up to $500+).