P0426 Code: Catalyst Temperature Sensor Circuit Range/Performance (Bank 1, Sensor 1)
🟠 Moderate severity · drivable
Drivable, but the computer can't trust the converter temperature reading, so get it diagnosed soon.
What P0426 means
The catalyst temperature sensor before the catalytic converter on bank 1 is sending a signal that is out of the expected range or changes too slowly. The computer uses this sensor to watch converter temperature, so a bad signal can affect emissions control.
Symptoms
- Check engine light is on
- Reduced fuel economy
- Possible failed emissions test
- Usually no drivability problems
Common causes
- most common: Faulty catalyst temperature sensor
- common: Damaged wiring or loose connector at the sensor
- less common: Exhaust leak near the sensor
- rare: Faulty PCM
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect the wiring and connector and repair any damage | Yes | $20–100 |
| Replace the catalyst temperature sensor | Yes | $60–200 |
| Have a shop test the circuit and PCM if the sensor checks out | Mechanic | $80–150 |
Frequently asked questions
Can I drive with a P0426 code?
Yes, it's a sensor signal problem, not an engine failure. Get it checked soon to avoid emissions issues.
What does P0426 mean?
The catalyst temperature sensor on bank 1 is sending a signal outside the normal range, so the computer can't trust the converter temperature reading.
How much does it cost to fix P0426?
Usually $60–200 for a new sensor, plus a little more if a shop installs it or repairs wiring.
Related codes
P0427
P0427 Code: Catalyst Temperature Sensor Circuit Low (Bank 1, Sensor 1)
P0428P0428 Code: Catalyst Temperature Sensor Circuit High (Bank 1, Sensor 1)
P0436P0436 Code: Catalyst Temperature Sensor Circuit Range/Performance (Bank 2, Sensor 1)
Related guide: How to Reset a Check Engine Light →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.