Daikin fault codes
29 codes from Daikin plates on FieldBench. Same number on another maker is a different code.
The list stays open.
- Status
% / run status
Modulating run, not a fault
Display showing a firing percent or a run word is status.
1 plate
- Lockout
b0
Blower motor not running
IFC commanded the serial ECM and does not see it run.
4 plates
- Lockout
b1
Blower motor communication
IFC lost serial comms with the circulator.
4 plates
- Lockout
b2
Blower HP / shared-data mismatch
Connected motor horsepower does not match the shared data set.
4 plates
- Lockout
Comm
ABCD / outdoor drop
ComfortBridge data pair only. Invalid as a diagnosis on a 24V Y1/Y2 hookup.
2 plates
- Lockout
d0
Data not yet on network
Communicating pair is wired and the IFC has no shared data (new board, missing memory card, learn not done).
4 plates
- Lockout
E0
Retry / recycle lockout
Failed to sense flame after the retry limit (typically three trials). One-hour-class auto retry.
4 plates
- Lockout
E1
Low-stage PS stuck closed
Low-fire pressure switch is made with the inducer off.
3 plates
- Lockout
E1 / E2 / E8 / E9
Inducer / pressure band (if shown)
On this modulator these letters are a prove-band / inducer path, not DM96VC low-vs-high discrete switches. Confirm on the DM97MC door card.
1 plate
- Lockout
E2
Low-stage PS open
Inducer on low, low-fire switch never closes. Classic 96% trap / PVC.
3 plates
- Protect
E3
Open limit / rollout circuit
Primary, auxiliary, or rollout opened. ComfortNet bundles these on E3 — inspect rollout before you treat it as a dirty filter.
4 plates
- Hazard
E4
Flame when no flame should be present
Rod sees flame with the valve de-energized.
4 plates
- Protect
E5
Open fuse
24 V automotive fuse on the IFC is open.
4 plates
- Protect
E6
Low flame signal
Flame present, µA below the IFC threshold.
4 plates
- Lockout
E7
Igniter / no-ground
Open or cracked HSI, bad igniter connection, or missing equipment ground.
4 plates
- Lockout
E8
High-stage PS stuck closed
High-fire switch is made with the inducer not on high. Furnace may stay on low.
3 plates
- Lockout
E9
High-stage PS open
Inducer on high, high-fire switch never closes. Runs on low, will not go high.
3 plates
- Lockout
EA
Reversed polarity / ground
115 V L1/N reversed, 24 V transformer reversed, or poor chassis ground.
4 plates
- Lockout
EE
Bus / internal
ComfortNet / Daikin One data dropped, or (on some dates) no 115 V / internal IFC fault. Stat English tells you which.
4 plates
- Lockout
HPS
High pressure
Outdoor airflow, overcharge, or restriction.
4 plates
- Lockout
HPS / LPS
Pressure protection
Still real on an inverter.
1 plate
- Lockout
Hum / no start
Cap / start
Compressor hums, outdoor fan may run.
2 plates
- Status
idle / Ht1 / Ht2 / CF
Status, not a fault
Ready, low heat, high heat, or continuous-fan CFM on the triple display.
3 plates
- Lockout
Inverter
Drive overcurrent / overheat
L5/L4-class faults on the drive.
1 plate
- Lockout
L5 / E6
Compressor / drive
Inverter overcurrent (L5) or compressor start fail (E6). Inverter-SKU language.
1 plate
- Lockout
LPS
Low pressure
Low-pressure / freeze protection. Charge, indoor airflow, metering.
2 plates
- Lockout
LPS / freeze
Low pressure
Charge, indoor airflow, metering.
2 plates
- Protect
No Y
Outdoor silent
No 24 VAC at the contactor or the coil is open.
2 plates
- Lockout
U4
Indoor/outdoor comm
Data pair between this outdoor and the communicating indoor is down.
1 plate