E09 = blower fan failure. The control sends a command to start the blower; the hall sensor doesn\'t confirm correct RPM. Lockout for safety (no fan = no exhaust = unsafe combustion).
Diagnostic sequence
1. Listen for blower start
- On a call for heat or DHW, the blower should spin up audibly before ignition
- Silent = motor not energized OR motor failed
- Whining/grinding = bearings worn, motor near end of life
2. Blower power verification
- 120V at blower terminals during start sequence (multimeter)
- No voltage = control board not commanding; may be control board fault
- Voltage present but no spin = motor or capacitor fault
3. Capacitor check
- Many Lochinvar blowers use a run capacitor (3-5 μF typical)
- Capacitor swells or fails = motor won\'t start
- Replace capacitor first ($15-25); often fixes apparent motor failure
4. Hall sensor / tach signal
- The blower has a hall sensor reporting RPM to the control
- If the motor spins but hall reports no signal = bad sensor or wiring
- Bad tach signal triggers E09 even with healthy motor
5. Vent obstruction check
- Blocked PVC vent (snow, insect nest, debris) = high back-pressure = blower can\'t reach target RPM
- Inspect intake and exhaust terminations
Cost
- Capacitor: $15-25
- Blower motor replacement: $250-450 (OEM)
- Hall sensor: $40-80 (sometimes integrated with motor)
- Contractor labor: $200-400
Bottom line
E09 = blower issue. Capacitor first (cheap test), then motor, then vent obstruction. If under warranty, contractor service through Lochinvar covers replacement.