Chevrolet P1138: HO2S (Sensor 2) Voltage Too High

Is your scanner showing Chevrolet P1138?
No worries. We'll show you what it means and how to deal with it.

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Chevrolet P1138: HO2S (Sensor 2) Voltage Too High

DIY Difficulty Level
Repair Cost
Can I Still Drive?
Yes (Short-term only)

What Does The Chevrolet P1138 Code Mean?

The engine is in deceleration fuel cut-off (DFCO)

What Are The Potential Causes Of The Chevrolet P1138 Code?

  • A rich exhaust–An overly rich exhaust may load the catalyst, causing high HO2S 2 signal voltages.
  • Silicone contamination–Silicone contamination of HO2S 2 could cause a false rich condition.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

GM, 2013, Service Bullettin – Prior To Any Circuit Testing.

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