Reductant Temperature Sensor Circuit Malfunction
The P2042 code indicates a problem in the reductant temperature sensor circuit, which monitors the temperature of diesel exhaust fluid (DEF) in the selective catalytic reduction (SCR) system. This sensor is critical for proper DEF injection and emissions control. When the circuit voltage is out of range, the PCM triggers this code, potentially leading to reduced engine performance and increased emissions.
1. Most Common Causes
- Faulty reductant temperature sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor or PCM
- Corroded or damaged connector
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Increased diesel exhaust fluid consumption
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve freeze frame data and confirm the code.
Step 2: Visually inspect the reductant temperature sensor and its wiring for damage or corrosion.
Step 3: Test the sensor resistance with a multimeter and compare to manufacturer specifications.
Step 4: Check for continuity and shorts in the circuit between the sensor and PCM.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it may cause reduced engine performance and increased emissions. The vehicle may enter limp mode, limiting speed and drivability.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on whether the sensor or wiring needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.