Error code

OBD2 P0133

OBD2P0133
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

P0133 indicates that the heated oxygen sensor (HO2S) on bank 1, sensor 1 is not responding quickly enough to changes in exhaust composition.

Symptoms

  • Engine may run rough at idle or stall frequently
  • Hesitation upon acceleration
  • Increased fuel consumption
  • Black smoke from tailpipe

Common Causes

  • Oil fouling on the oxygen sensor, common in high oil consumption vehicles like BMW and Mercedes-Benz
  • Defective oxygen sensors
  • Problems with the heater control circuit preventing full heating of the sensor element
  • Large exhaust leaks or vacuum leaks affecting air/fuel mixture

Diagnosis

  1. Check for other codes and resolve them first if present.
  2. Inspect wiring and connectors for damage or corrosion.
  3. Test electrical values including reference voltage, ground, continuity, and resistance of the oxygen sensor circuit.
  4. Replace faulty oxygen sensors if necessary after identifying fouling or malfunction.

Fixes

  • Clean MAF (Mass Airflow Sensor) element with an approved cleaner to resolve fuel metering issues.
  • Replace the faulty oxygen sensor and ensure proper installation away from heat sources.

FAQ

What does P0133 mean?

P0133 indicates a slow response time in the heated oxygen sensor (HO2S) on bank 1, sensor 1.

How do I fix P0133?

Fixes include cleaning the MAF element or replacing the faulty oxygen sensor after thorough diagnosis.

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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