P2604 OBD II Trouble Code Intake Air Heater A Circuit Range Performance

How to diagnose, repair, and info on symptoms and causes of a P2604 engine code which applies to diesel vehicles with an air intake heater. This is a circuit problem that relates to range or performance. Also includes links to relevant forum discussions on the code.

Symptoms of P2604 OBD II Trouble Code

  • Engine will not start
  • Longer than normal cranking time
  • Check Engine Light illuminated
  • Rough idle at cold temperatures
  • Engine stalls

Common Causes of P2604 OBD II Trouble Code

  • Faulty heater element relay
  • Detective heater element
  • Faulty temperature sensor
  • Corroded or damaged connector
  • Damaged or restricted air duct
  • Faulty or damaged wiring
  • Defective Blower motor
  • Faulty PCM

Severity of P2604 OBD II Trouble Code

The severity of this code is normally moderate, but can be severe based on the specific malfunction.