Error code

OBD2 P0143

OBD2P0143
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Circuit Low Voltage.

Severity

moderateCan drive, but emissions may be affected.

Summary

P0143 indicates low voltage in the heated oxygen sensor circuit for Bank 1 Sensor 3, which is located downstream of the catalytic converter.

Common Causes

  • Faulty heated oxygen sensor (HO2S)
  • Circuit fault due to damaged wiring harness or connectors
  • Exhaust leak between the TWC and HO2S

Diagnosis

  1. Check fuses and wiring for damage or corrosion.
  2. Inspect exhaust system for leaks.
  3. Test circuit continuity and resistance between ECM and HO2S.
  4. Verify sensor internal resistance and compare live data from the HO2S and AFR sensor.

Fixes

  • Replace faulty heated oxygen sensor (HO2S).

FAQ

What does P0143 mean?

P0143 indicates low voltage in the heated oxygen sensor circuit for Bank 1 Sensor 3, which is located downstream of the catalytic converter.

How do I diagnose P0143?

Diagnose by checking fuses and wiring, inspecting exhaust system for leaks, testing circuit continuity and resistance, and verifying sensor internal resistance.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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