P0138
Sistema
Powertrain (Emissions)
Scanner richiesto
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.

Sintomi comuni

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

Cause tipiche

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

Quale scanner ti serve?

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

Usa dati live e freeze frame prima di sostituire componenti. I codici ABS, SRS e U richiedono spesso uno scanner mult sistema.

Consigli diagnostici

  • Registra il freeze frame quando il codice compare la prima volta
  • Cancella il codice solo dopo aver risolto la causa
  • Controlla i codici pending correlati
  • Verifica che la batteria sia sopra 12,4 V prima di sospettare un sensore

Scanner FOXWELL consigliati

Domande frequenti

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.