Reductant Tank Heater Control Circuit/Open
The P202A code indicates a malfunction in the reductant (DEF) tank heater control circuit. The powertrain control module (PCM) has detected an open or short in the circuit that controls the heater element inside the DEF tank. This heater prevents the DEF fluid from freezing in cold temperatures. An open circuit means there is a break in the electrical path, preventing the heater from operating.
1. Most Common Causes
- Open or short in the reductant tank heater circuit wiring or connector
- Faulty reductant tank heater element
- Blown fuse or relay for the heater circuit
- Corroded or damaged electrical connections
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased diesel exhaust fluid (DEF) consumption
- Possible inability to start in cold weather
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
Step 2: Visually inspect the wiring and connectors to the reductant tank heater for damage, corrosion, or loose connections.
Step 3: Test the heater circuit for continuity and resistance using a multimeter. Compare readings to manufacturer specifications.
Step 4: Check the fuse and relay for the heater circuit; replace if blown.
Step 5: If all else is fine, replace the reductant tank heater assembly.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It may be safe in warm weather, but in cold temperatures the DEF can freeze, potentially causing damage to the SCR system and leading to reduced performance or a no-start condition. It's best to repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause. A simple fuse replacement is cheap, while replacing the heater assembly may be higher.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.