Skip to main content
Error code reference
Denso Air Conditioner Error Codes
39 error codes documented with diagnostic procedures.
Have your model number? Get codes specific to your unit.
ALDetection of unit stop signal from fire alarm systemALRMUnit stop signal detected from fire alarm systemASCondensate pump problemCFLoss of cooling detectionDFFreezing abnormalityE01WMC room thermistor (RTS1) failureE02Evaporator inlet air thermistor (RTS2) failureE03Condenser inlet air thermistor (ODS) failureE04Condenser thermistor (CTS1) failureE05Evaporator pipe inlet thermistor (CTS2) failureE06Evaporator pipe outlet thermistor (CTS3) failureE07Condensation overflow detected from optional condensate pumpE08WMC communication errorE09Evaporator fan motor lockedE1Room thermistor connection problemE10Condenser fan motor lockedE11STI module communication errorE14Compressor over currentE15Compressor lock failureE16Compressor phase interruption abnormalityE17Motor position detection abnormalityE18Input overcurrentE19Power device temperature abnormalityE2Freeze protection thermistor connection problemE20DC voltage abnormalityE21Power device damage abnormalityE22Circuit malfunctionE4Activation of protective deviceFLOvercurrent relay (thermal relay) protection activatedFTFreeze protection thermistor defectFZDefrost status / freeze condition indicated; evaporator outlet pipe temperature displayed.HPActivation of high pressure switchIREvaporator fan motor reverse rotation abnormalityLOCKEDKey lock mode is activeOLCompressor overload relay activated due to high temperature build-up in compressor.ORCondenser fan motor reverse rotation abnormalityPUCondensation overflow detectedRTRoom thermistor defectTANKThe drain tank switch has shut off the unit because the drain tank is full (full tank LED…
Get the full diagnostic procedure for any code
Step-by-step tests, expected values, wiring diagram references, and verified part numbers.
Get Started $9.95 3-day pass$29/month for unlimited access to all brands and Max AI diagnostics.
Common questions
How do I find the error code on my Denso Air Conditioner?
Most Denso air conditioners show the code directly on the control panel display. If your model has no display, it can be read by entering diagnostic mode with the key sequence for your model. The full procedures include model-specific instructions for reading codes.
Are these codes specific to my model?
The codes here apply broadly to Denso air conditioners. Meanings and diagnostic steps can vary by model and production year, so enter your model number for model-specific information and procedures.
What do I do if my code is not listed?
Some codes are model-specific or only appear in diagnostic mode. Enter your model number to get codes specific to your unit, or contact us. We update the database continuously from manufacturer service documentation.
How much does it cost to access the full diagnostic procedures?
A 3-day pass is $9.95 one-time and gives full access to all brands, codes, and procedures. Monthly access is $29/month with unlimited access to everything including Max AI diagnostics.