P0428 — Catalyst Temperature Sensor Low Input (Bank 1)
Can drive — fix at your convenience.
What P0428 means
This code is set when the catalyst temperature sensor on bank 1 reports a voltage that's lower than expected, suggesting a short, an open circuit, or a failing sensor. It's usually an electrical issue rather than an actual catalyst fault. Repairs typically involve inspecting the wiring and connector and replacing the sensor if needed, which is generally a low-cost fix.
Common symptoms
- Check engine light is on
- Failed emissions or smog test
- No real change in performance or drivability
- Abnormally low temperature reading on a scan tool
- Possible intermittent warning light
Common causes
- Short to ground in the sensor circuit
- Failing catalyst temperature sensor
- Corroded or damaged sensor connector
- Open or broken wiring to the sensor
- Poor ground or power supply to the sensor
Typical repair cost
$120 – $450
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0428 code?
Yes, in most cases. It's a sensor-signal issue that doesn't affect how the car drives or its safety. The main reasons to fix it are to turn off the check engine light and pass emissions testing.
How much does it cost to fix a P0428?
This is a low-cost code to repair. Most fixes range from $120 to $450, covering wiring repairs or a temperature sensor replacement with labor.
Is a P0428 code serious?
No, it's low severity. It almost always reflects an electrical or sensor fault rather than a damaged catalyst, so it won't leave you stranded. It's still worth fixing so it doesn't hide other developing issues.
What does 'low input' mean in P0428?
It means the sensor's voltage signal is reading lower than the computer expects, often from a short circuit or a failing sensor. It's about the electrical signal, not the actual exhaust temperature.