Reductant Heater Control Circuit Performance
The P20BE code indicates a performance issue in the reductant heater control circuit, which is part of the Selective Catalytic Reduction (SCR) system. This heater warms the diesel exhaust fluid (DEF) to prevent freezing and ensure proper injection. The Powertrain Control Module (PCM) detects that the heater circuit is not operating within expected parameters, often due to high resistance, open circuit, or short circuit. This can lead to inadequate DEF heating, causing emissions non-compliance and potential SCR system damage.
01. Most Common Causes
- Faulty reductant heater element
- Open or shorted wiring in the heater circuit
- Corroded or loose electrical connectors
- Failed reductant heater relay or fuse
- Defective PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Increased diesel exhaust fluid consumption
- Poor fuel economy
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the reductant heater wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the heater circuit resistance using a multimeter; compare to manufacturer specifications.
Step 4: Check the heater relay and fuse for proper operation.
Step 5: If all else is okay, test the PCM output to the heater circuit.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances. The vehicle may enter limp mode, and continued driving can damage the SCR system or cause emissions violations.
How much does it cost to fix?▼
Typical repair costs range from $50 to $150 for parts like a relay or fuse, but if the heater element or wiring needs replacement, costs can be higher.