P0138
System
Powertrain (Emissions)
Benötigter Scanner
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)

Understand P0138, common causes, and the right FOXWELL scanner to diagnose it.

Downstream O2 sensor bank 1 reading high — often failed sensor after catalytic converter or rich running condition.

Häufige Symptome

  • Check engine light
  • Failed emissions
  • May appear with P0420

Typische Ursachen

  • Failed downstream O2 sensor
  • Rich fuel mixture
  • Exhaust leak
  • Contaminated sensor from oil/coolant

Welchen Scanner brauchen Sie?

Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Nutzen Sie Live-Daten und Freeze Frame, bevor Sie Teile tauschen. ABS-, SRS- und U-Codes erfordern meist einen Vollsystem-Scanner.

Diagnose-Tipps

  • Freeze Frame erfassen, wenn der Code erstmals gesetzt wird
  • Code erst nach Behebung der Ursache löschen
  • Auf verwandte pending codes prüfen
  • Batteriespannung über 12,4 V prüfen, bevor Sie Sensoren verdächtigen

Empfohlene FOXWELL Scanner

Häufig gestellte Fragen

Can I diagnose P0138 with a basic code reader?
P0138 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with P0138?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.