GMC Sierra
P0138
The P0138 code indicates a high voltage signal from the oxygen sensor located in the downstream position of the catalytic converter on a GMC Sierra T1XX (2019-Present). This code typically suggests that the sensor is reporting a voltage higher than the expected range, which can lead to poor engine performance and increased emissions.
1 SolutionP-CodePowertrain
P
Error Code Type
Powertrain
Components
1 affected
Exhaust System
Symptoms
5 common
- •Check engine light illuminated
- •Decreased fuel efficiency
- •Rough idling or engine misfires
- +2 more
Most Affected Generations
1 generation
T1XX
1
Top Affected Components
1 component
Exhaust System
1
Severity Levels
1 level
medium
1
Quick Facts
1
Total Solutions
1
Affected Components
5
Common Symptoms
1
Generations
All Solutions
Showing 1 of 1 solution for error code P0138 across all generations.