Error code

OBD2 P0139

OBD2P0139
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Circuit Slow OBDResponse.

Severity

moderateCan drive, but performance issues may occur.

Summary

Code P0139 indicates a slow response from the heated oxygen sensor (HO2S) 2 on bank 1, which is located downstream of the catalytic converter. This can affect the monitoring of the converter's 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
  • Open circuits
  • Blown fuses (where applicable)
  • Defective oxygen sensors
  • Heavily fouled or contaminated oxygen sensors

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 stability.
  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 and connectors as needed.
  • Replace the faulty oxygen sensor if necessary.

FAQ

What does P0139 mean?

P0139 indicates a slow response from the heated oxygen sensor (HO2S) 2 on bank 1, which can affect monitoring of the catalytic converter's efficiency.

How do I diagnose P0139?

Diagnose by checking wiring and connectors for damage, testing live data streams, performing electrical tests, and inspecting the oxygen sensor for issues.

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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