Denso Air Conditioner Error Code E22

E22 indicates a circuit malfunction in the STI internal current and voltage detection circuit, caused by either a short or an open circuit condition within that path. The STI circuit monitors electrical levels to protect key components during operation. When this monitoring circuit fails, the unit shuts down to prevent damage. The relay board is the primary component involved in this fault.

No, continuing to operate the unit while E22 is active is not advisable. The error indicates the internal circuit responsible for monitoring current and voltage levels is not functioning correctly, which means the system cannot detect electrical faults that could damage the compressor or fan motor. The unit typically suspends operation automatically when this code appears, which is the intended protective response. Leave the unit off until the fault is diagnosed and repaired.

Repair costs for E22 vary depending on parts pricing and local labor rates, but you should expect to pay for a replacement relay board plus the technician's time to install it and perform the required fan motor initialization. Relay board components for commercial or mini-split style units typically range from moderately priced to higher cost depending on the specific model. Total repair costs including labor generally fall somewhere in the range of a few hundred dollars, but obtaining a quote specific to your unit model is recommended.

The recommended repair procedure starts with replacing the relay board, which houses the STI current and voltage detection circuit. After installing the new relay board, the fan motor must be initialized to allow the new board to establish proper communication and calibration with the motor controller. Skipping the initialization step can cause the error to persist even after a correct board replacement. This repair should be performed by a qualified technician familiar with the unit's electrical systems.

A simple power reset is unlikely to permanently clear E22 because the fault points to a hardware failure in the relay board's detection circuit, not a transient software glitch. The error may temporarily disappear after a reset but will return once the unit attempts normal operation and the faulty circuit is active again. Proper resolution requires physical inspection and, in most cases, relay board replacement followed by fan motor initialization.