P0138
Sistema
Powertrain (Emissions)
Escáner necesario
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.

Síntomas habituales

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

Causas típicas

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

¿Qué escáner necesita?

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

Use datos en vivo y freeze frame antes de cambiar piezas. Códigos ABS, SRS y U suelen requerir un escáner de todos los sistemas.

Consejos de diagnóstico

  • Registre el freeze frame cuando se active el código
  • Borre el código solo tras corregir la causa
  • Revise códigos pendientes relacionados
  • Verifique que la batería esté por encima de 12,4 V antes de sospechar sensores

Escáneres FOXWELL recomendados

Preguntas frecuentes

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.