P0426: Catalyst Temperature Sensor Range/Performance (Bank 1, Sensor 1)
The P0426 code indicates that the Engine Control Module (ECM) has detected a malfunction in the catalyst temperature sensor circuit for Bank 1, Sensor 1. This sensor monitors the temperature of the catalytic converter to ensure it is operating efficiently. The code is set when the sensor signal is out of the expected range or the sensor response is slower than anticipated. Common causes include a faulty sensor, wiring issues, exhaust leaks, or a failing catalytic converter.
01. Most Common Causes
- Faulty catalyst temperature sensor
- Damaged or corroded wiring/connectors
- Exhaust leaks near the sensor
- Failing catalytic converter
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Decreased fuel efficiency
- Possible failed emissions test
- Rough engine performance or hesitation
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the sensor and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance and voltage output with a multimeter and compare to manufacturer specifications.
Step 4: Check for exhaust leaks upstream of the sensor using a smoke machine or visual inspection.
Step 5: If all else is fine, replace the catalyst temperature sensor and clear the code.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive short distances, but prolonged driving may cause further damage to the catalytic converter or affect emissions. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY sensor replacement, or $150 to $300 if professionally installed, including parts and labor.