P0438 — Catalyst Temperature Sensor Low Input (Bank 2)
Can drive — fix at your convenience.
What P0438 means
This code sets when the catalyst temperature sensor on bank 2 sends a voltage signal that is too low, often caused by a short to ground in the wiring or a failed sensor. It can also come from a corroded connector or, less commonly, a problem in the engine computer's circuit. Typical repairs include replacing the sensor and repairing any shorted or damaged wiring.
Common symptoms
- Check engine light is on
- Failed emissions or smog test
- No noticeable change in drivability for most drivers
- Low or zero temperature reading on a scan tool
- Possible minor dip in fuel economy
Common causes
- Failed catalyst temperature sensor on bank 2
- Short to ground in the sensor wiring
- Corroded or damaged electrical connector
- Chafed wiring touching the exhaust or chassis
- Rarely, a fault in the engine control module circuit
Typical repair cost
$120 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0438 code?
Usually yes. The car typically drives normally because this is a sensor and wiring issue, not an engine fault. You'll want to fix it before an emissions test, but there's no rush from a safety standpoint.
How much does it cost to fix a P0438?
Most repairs land between $120 and $400. Replacing the sensor is inexpensive, and the bigger variable is how much labor is needed if wiring has to be traced and repaired.
Is a P0438 code serious?
It's a low-severity code. It won't strand you or harm the engine, but it keeps the check engine light on and prevents passing emissions, so it should be addressed at a convenient time.
What does low input mean in a P0438 code?
It means the sensor's voltage signal is reading lower than expected, often because the wiring is shorted to ground or the sensor has failed internally. A technician will test the circuit to find which it is.