Combustion Air Fan Circuit: Open

Test 1:

SYMPTOM
B1821 COMBUSTION AIR FAN CIRCUIT: OPEN

WHEN MONITORED
After DCHA activation, when the system is in a steady state of operation.

SET CONDITION
This DTC will set if the DCHA Control detects no-load voltage on the Combustion Air Fan circuit output pin.

POSSIBLE CAUSES
- Combustion air fan/DCHA control unit fault