Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0137: 1/2 O2 Sensor Shorted To Ground: Description
1/2 Heated Oxygen Sensor (HO2S) voltage is monitored at a cold start, provided engine coolant temperature is less than 98°F (37°C), ambient/battery temperature is within plus or minus 27°F of engine coolant temperature and engine coolant temperature was more than 170°F (77°C) when ignition was last turned off. DTC will set in Powertrain Control Module (PCM) memory when PCM senses 1/2 HO2S voltage is less than .156 volt for 28 seconds after engine is started. Possible causes are: defective 1/2 HO2S, signal circuit shorted to ground, sensor ground or heater ground, or defective PCM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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