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.
Code P0133, Heated Oxygen Sensor Slow Response: Notes
"S" & "T" SERIES 4.3L (VIN W) BANK 1, SENSOR 1
Control module supplies and monitors a voltage of about .45 volt between control module HO2S low reference circuit and HO2S signal circuit. If read with a 10-megohm DVOM, voltage may read as low as .32 volt. HO2S varies voltage within a range of about 1.0 volt (rich) to .10 volt (lean). Sensor is like an open circuit and produces no voltage when less than about 600°F (360°C). Open loop operation is caused by Codes P0131, P0132, or an open or cold sensor. Code P0132 will cause system to operate in open loop. Control module will illuminate Malfunction Indicator Light (MIL).
- Checks for other codes.
- Checks for physical damage to engine components and converter.
- Checks fuel injector and isolates sensor.
NO RELATED
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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.