Navien CH-180, Service Manual, Page: 100 / 155

98
Error occurrence conditions and check items
5.21. 27Error
Error Description
If an error (open: 0.1±0.1V or lower / short-circuit: 4.5±0.2V or higher) in the air
pressure sensor is detected continuously for 3 seconds, or if the air pressure
sensor voltage of 1.20V is detected before pre-purge, the system displays the error
message 27E on the remote controller.
Check the assembly of the connector of the air pressure sensor.
Check the voltage of the air pressure sensor.
27E
Abnormal
air pressure
sensor
error
Check
items
During fan motor operation, is
the output voltage of APS
normal ?
Yes
No
Replace APS
During fan motor stop, is the
output voltage of
APS normal ?
Yes
No Replace APS
Check the voltage between black and white wire of
CN 6: 0.2 - 0.6VDC
Check the voltage between black and white wire of
CN 6: 1 - 4VDC
Replace PCB
© Navien Ameri c a I n c . 20 1 0 CH series servi c e Manua l Version 1 .0