Exhaust Gas Temp Sensor Circuit Range/Performance Bank 1 Sensor 3
The P242B code indicates that the Engine Control Module (ECM) has detected a performance or range issue with the exhaust gas temperature (EGT) sensor located in Bank 1, Sensor 3 (downstream of the diesel particulate filter or catalytic converter). This sensor monitors exhaust temperature to protect components and optimize emissions. The code sets when the sensor signal is out of expected range or responds too slowly, often due to sensor degradation, wiring faults, or exhaust leaks.
1. Most Common Causes
- Faulty exhaust gas temperature sensor
- Wiring or connector issues (open, short, corrosion)
- Exhaust leaks near the sensor
- ECM software or calibration error
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Possible limp mode or reduced engine power
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect EGT sensor wiring and connector for damage or corrosion.
Step 3: Compare sensor resistance and voltage readings to manufacturer specifications.
Step 4: Check for exhaust leaks upstream of the sensor.
Step 5: If all else is normal, replace the EGT sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe for short trips, but prolonged driving may cause reduced performance, poor fuel economy, and potential damage to emission components. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for the sensor part, plus labor if you have a mechanic replace it. DIY replacement can save on labor costs.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.