P0438

Catalyst Temperature Sensor Circuit High Bank 2 Sensor 1

Q: Is it safe to drive with P0438?

Yes. It's a temperature-sensor circuit fault that doesn't affect starting or normal running. Repair it so the catalyst monitors work and the car can pass inspection.

Q: Can I just clear P0438?

It will return unless the sensor or its wiring is repaired.

Catalyst temperature sensor / emissions Generic OBD-II Medium

What it means

P0438 means the signal from the bank 2, sensor 1 catalyst temperature sensor is reading higher than its valid range. This sensor monitors the catalytic converter's temperature so the computer can protect it and run its emissions checks. A high (out-of-range) signal points to the sensor, an open or short in its wiring, or a bad connection rather than an engine fault, so the car normally starts and drives fine.

Medium

Can I keep driving? You can keep driving. This is a sensor-circuit fault that affects emissions monitoring, not how the engine starts or runs.

Real-world scan data

Seen in

116

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Appears alongside · share of P0438 scans

P0645in 63.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Usually no noticeable change in how the car drives
Catalyst-related emissions monitors may not complete
Possible failed emissions readiness check

Common causes

Most likely first

Faulty catalyst temperature sensor (bank 2, sensor 1) reading highLikely
Signal wire open or shorted to voltageCommon
Corroded or loose sensor connectorCommon
Damaged wiring near the hot exhaustLess often
Failed ECM (rare — check the sensor and wiring first)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code is on the bank 2 sensor 1 catalyst temperature sensor.
Inspect the sensor connector and harness for an open, a short to voltage, corrosion, or heat damage.
Check the sensor's reference and ground circuits back to the ECM.
Measure the sensor's resistance/output and compare against spec at a known temperature.
Replace the catalyst temperature sensor if it reads out of range, then clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0438?+

Yes. It's a temperature-sensor circuit fault that doesn't affect starting or normal running. Repair it so the catalyst monitors work and the car can pass inspection.

Can I just clear P0438?+

It will return unless the sensor or its wiring is repaired.

Read & clear P0438 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX