Error code

OBD2 P0142

OBD2P0142
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Circuit.

Severity

moderateCan drive, but performance issues and reduced fuel economy may occur.

Summary

P0142 indicates a malfunction in the heated oxygen sensor (HO2S) circuit for Bank 1 Sensor 3. This sensor is located downstream of the catalytic converter and monitors its efficiency.

Symptoms

  • Stored trouble code
  • Rich or lean running conditions
  • Reduced fuel economy
  • Engine hesitation or stumbling upon acceleration
  • Rough idling

Common Causes

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors
  • Blown fuses (where applicable)
  • Defective oxygen sensors
  • Heavily fouled or contaminated oxygen sensors
  • PCM failure (rare)

Diagnosis

  1. Check for other codes and ensure the engine is in perfect running condition.
  2. Inspect wiring and connectors for damage or corrosion.
  3. Monitor live data streams to check sensor temperature and signal voltage.
  4. Perform reference, input, resistance, ground, and continuity tests on wiring.
  5. Test oxygen sensor resistance and inspect it for discoloration or deposits.

Fixes

  • Replace damaged wiring or connectors.
  • Replace blown fuses (if applicable).
  • Replace defective oxygen sensors.

FAQ

What does P0142 mean?

P0142 indicates a malfunction in the heated oxygen sensor circuit for Bank 1 Sensor 3, which is located downstream of the catalytic converter.

How do I diagnose P0142?

Diagnose by checking wiring and connectors, performing electrical tests on the sensor circuit, and testing the oxygen sensor itself for resistance and physical condition.

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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