Catalyst Temperature Sensor High (Bank 2)
The P0438 code means the vehicle's onboard diagnostic system has detected: Catalyst Temperature Sensor High (Bank 2). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $80 - $400 (parts and labor)
Reads enhanced codes and shows real-time O2 sensor data. Verify the cat is actually bad before dropping $1,000+ on a replacement.
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Common Symptoms
- Check Engine Light illuminated
- Scan tool shows abnormally high Bank 2 catalyst temperature
- Possible overheating warning
- No drivability issues in most cases
Probable Causes (Ranked by Likelihood)
- Faulty Bank 2 catalyst temperature sensor reading high Very High
- Short to voltage in Bank 2 sensor signal wire High
- Open ground wire causing signal to float high Moderate
- Genuine catalyst overheating from Bank 2 misfires Moderate
Step-by-Step Diagnostic Procedure
-
Compare scan tool Bank 2 catalyst temperature to an infrared thermometer measurement
-
Check if the reading is plausible -- readings above 1800 degrees F likely indicate a sensor fault
-
Verify Bank 2 sensor ground wire continuity
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Check signal wire for short to voltage
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If readings appear accurate, check for Bank 2 misfires or rich fuel condition
Frequently Asked Questions
Can I drive with code P0438?
Drive short distances only until diagnosed. While a faulty sensor is most likely, if the Bank 2 catalyst is genuinely overheating, continued driving risks a fire or catalyst destruction.
Is P0438 the Bank 2 version of P0428?
Yes. P0428 covers Bank 1 catalyst temperature sensor high and P0438 covers Bank 2. The diagnostic process is identical on the opposite bank.
How do I verify if the catalyst is actually overheating?
Use an infrared thermometer on the Bank 2 exhaust pipe near the converter. If it matches the abnormally high scan tool reading, the overheating is real and likely caused by misfires or a rich condition.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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