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Error code reference
LG Air Conditioner Error Code CH40
CT sensor open or short circuit - PCB current detection abnormality.
SourceLG Air Conditioner - Tech Sheet: LP-Y Series Specifications
Diagnostic procedure
The full CH40 procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Replace outdoor unit PCBA without separate inspection (burn-out of outdoor PCBA components).
SourceLG Wall Mounted Air Conditioner - Service Manual: General Inverter Typep. 28, 70
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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Where this code is documented
2 manuals in the MyPros+ library document this code for LG air conditioner.
Models covered by the manuals that document this code
75,000+ service documents · 20,000+ error codes · 100+ brands
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