P0427 Code: Catalyst Temperature Sensor Circuit Low (Bank 1, Sensor 1)
🟠 Moderate severity · drivable
Drivable, but the computer can't read converter temperature, so fix it soon.
What P0427 means
The signal from the catalyst temperature sensor on bank 1 is lower than it should be, often near zero. This usually points to a short to ground, damaged wiring, or a failed sensor.
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: Short to ground or damaged wiring
- common: Corroded or loose connector
- rare: Faulty PCM
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect the circuit and repair shorts or damaged wiring | Yes | $20–100 |
| Replace the catalyst temperature sensor | Yes | $60–200 |
| Have the PCM checked if the sensor and wiring are good | Mechanic | $100–200 |
Frequently asked questions
Can I drive with a P0427 code?
Yes, the car should drive normally, but the computer can't read converter temperature. Get it diagnosed soon.
What does a circuit low code mean?
The sensor's signal is reading too low, which usually points to a short to ground, bad wiring, or a dead sensor.
How much does it cost to fix P0427?
$60–200 for a new sensor, or $20–100 for wiring repairs plus labor.
Related codes
P0426
P0426 Code: Catalyst Temperature Sensor Circuit Range/Performance (Bank 1, Sensor 1)
P0428P0428 Code: Catalyst Temperature Sensor Circuit High (Bank 1, Sensor 1)
P0437P0437 Code: Catalyst Temperature Sensor Circuit Low (Bank 2, Sensor 1)
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.