Reductant Tank Heater Control Circuit High
The P202C code indicates that the powertrain control module (PCM) has detected a high voltage condition in the reductant (DEF) tank heater control circuit. This heater is used to prevent diesel exhaust fluid from freezing in cold temperatures. A high voltage reading suggests a short to power, a faulty heater element, or a problem with the control module or wiring.
1. Most Common Causes
- Short to power in the heater control circuit
- Faulty reductant tank heater element
- Damaged wiring or connector
- Failed PCM or DEF control module
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Possible DEF system warning messages
- Difficulty starting in cold weather
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes.
Step 2: Visually inspect the heater wiring and connector for damage, corrosion, or shorts.
Step 3: Measure resistance of the heater element; compare to manufacturer specs.
Step 4: Check for voltage at the heater connector with the ignition on; if voltage is present when it shouldn't be, trace the short.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances, as the DEF system may not function properly, potentially leading to reduced engine power or emissions non-compliance.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on whether the heater element, wiring, or control module needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.