Error code

OBD2 P0146

OBD2P0146
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

O2 Sensor Circuit No Activity Detected.

Severity

highThe vehicle may be drivable but with significant performance issues. It is recommended to address the issue promptly.

Summary

P0146 indicates that the heated oxygen sensor (HO2S) on bank 1, sensor 3 is not sending any signal voltage to the PCM. This sensor is located downstream of the catalytic converter.

Symptoms

  • Severe driveability issues such as loss of power and hesitation upon acceleration
  • Increased fuel consumption
  • Visible black smoke from the tailpipe
  • Hard starting
  • Oil dilution due to over-fueling
  • Reduced spark plug life

Common Causes

  • Defective oxygen sensor
  • Damage or corrosion in wiring and connectors of the signal circuit
  • Blown fuse(s) in the heater control circuit (if applicable)
  • Contamination from oil or antifreeze
  • Faulty PCM (rare)

Diagnosis

  1. Check for other stored trouble codes and freeze frame data.
  2. Inspect wiring and connectors for damage or corrosion.
  3. Perform resistance, input voltage, ground, and continuity checks on all circuits associated with the sensor.
  4. Remove and inspect the oxygen sensor for discoloration or deposits.
  5. Replace the sensor if it does not meet manufacturer specifications.

Fixes

  • Replace the faulty oxygen sensor.

FAQ

What causes P0146?

Common causes include a defective oxygen sensor, damaged wiring and connectors in the signal circuit, blown fuses in the heater control circuit (if applicable), contamination from oil or antifreeze, and rarely, a faulty PCM.

How do I diagnose P0146?

Diagnose by checking for other codes, inspecting wiring and connectors, performing electrical checks on circuits associated with the sensor, removing and inspecting the oxygen sensor, and replacing it if necessary.

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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