P0428 OBD II Trouble Code Catalyst Temperature Sensor Circuit High (Bank 1, Sensor 1)

How to diagnose, repair, and info on causes of a P0428 engine code which involves the bank 1 sensor 1 catalyst temperature oxygen sensor circuit which is high. Also includes links to relevant forum topics on the code.

Symptoms of P0428 OBD II Trouble Code

  • Illuminated check engine light
  • Poor engine performance
  • Decreased fuel economy
  • Increased emissions

Common Causes of P0428 OBD II Trouble Code

  • Faulty oxygen sensor
  • Wiring problems
  • Exhaust air/fuel mixture out of balance
  • Faulty PCM/PCM programming

Severity of P0428 OBD II Trouble Code

The severity of this code is moderate. Symptoms of a P0428 engine code may include: