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.
P0155-O2 Sensor 2/1 Heater Performance: Notes
- When Monitored : Engine Running and Heater duty cycle greater than 0%.
- Set Condition : O2 Heater Temperature does not reach 575°C (959°F) within 90 seconds during monitoring conditions. Two Trip Fault.
| Possible Causes |
|---|
| FUSED ENGINE CONTROL RELAY OUTPUT CIRCUIT OPEN |
| O2 SENSOR HEATER CONTROL CIRCUIT SHORT TO VOLTAGE |
| O2 SENSOR HEATER CONTROL CIRCUIT SHORT TO GROUND |
| O2 HEATER CONTROL CIRCUIT OPEN |
| O2 HEATER ELEMENT |
| POWERTRAIN CONTROL MODULE |
For a complete Powertrain Control Module Circuit Diagram, refer to SCHEMATICS AND DIAGRAMS .
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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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