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.
Testing Procedure
O2 Signal - Connect DVOM between ME-SFI control module connector "C" terminals No. 31 and 32 (socket box terminals No. 23 and 24). Start engine and idle. Allow engine to idle for at least 2 minutes after engine coolant temperature reaches more than 176°F (80°C). Voltage should fluctuate by more than 0.3 volts between -0.2 volts and one volt. If voltage is okay, test is complete. If voltage is not okay, possible causes are right O2 sensor (before TWC) heater failure, wiring harness failure or defective right O2 sensor (before TWC - G3/4). To check right O2 sensor (before TWC) heater failure, go to DTC P0135: O2 SENSOR HEATING OF RIGHT O2 SENSOR UPSTREAM TWC (G3/4) .
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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.