Intake Air Heater A Circuit Open
The intake air heater (grid heater) on path A - used on cold-start of diesel engines to warm intake air for reliable combustion - has an open control circuit. Without it, cold-start emissions and idle quality on cold days suffer.
Affected components
- Intake air heater a
- Heater a relay
Common causes
- High likelihood: Open in harness, relay or heater element
- Low likelihood: Pin pushed back out of connector body
- Low likelihood: Cracked solder joint inside the module or sensor
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.