P0138
Système
Powertrain (Emissions)
Scanner requis
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.

Symptômes courants

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

Causes typiques

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

Quel scanner choisir ?

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

Utilisez les données en direct et le freeze frame avant de remplacer des pièces. Les codes ABS, SRS et U nécessitent souvent un scanner mult systèmes.

Conseils de diagnostic

  • Enregistrez le freeze frame lors de la première apparition du code
  • Effacez le code uniquement après avoir corrigé la cause
  • Vérifiez les codes en attente associés
  • Vérifiez que la batterie est au-dessus de 12,4 V avant de suspecter un capteur

Scanners FOXWELL recommandés

Questions fréquentes

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.