Error returns after every reset: corroded outdoor terminals
The York unit kept showing an E6 error that no reset would clear. The recurring code was a genuine fault, not a glitch. The cause turned out to be corroded wire connections at the outdoor unit, not the board a code like that suggests.
By Team Snowflake | Updated 24 Mar 2026
Case summary
York Wall-mounted7-12 years oldHDBJurong East, Singapore
- Concern
- The unit looked headed for an outdoor control board replacement, an expensive part the homeowner wanted to avoid.
- Found
- Corroded communication wire connections at the outdoor unit causing intermittent signal loss
- Key check
- Inspected outdoor wire connection point and found green oxidation on communication wire wire joints
- Result
- The E6 error cleared once the outdoor wire connections were cleaned and refitted. The unit has run without a single communication fault since, and the homeowner avoided the cost of a new board.
What we were told
The unit keeps showing an error code and shutting off. Two earlier visits had come and gone without the fault being traced. The homeowner feared the next step would be an expensive outdoor board replacement, paid for on a guess rather than a finding.
What we checked
On York systems, an E6 error means the indoor and outdoor units cannot talk to each other. That points to the wire link between them, so we started at the outdoor connection point where the communication wires join.
The E6 code reappeared on the indoor unit after every startup attempt, so the fault was steady, not random.
The indoor control board was sending communication signals normally, which ruled out the indoor side.
The communication wire between the two units was intact, with no visible damage along its run.
At the outdoor connection point, both communication wire joints showed green oxidation.
That corrosion left the contact loose and intermittent. The signal dropped under load as the connection warmed, which is why a reset only held for a short while.
What we found
The outdoor communication wire connections had corroded after years of humidity and condensation. The green oxidation on the wire joints raised the resistance in the circuit, so the signal cut out whenever the contact shifted. A York E6 error flags exactly this kind of communication failure. On a communication fault, the physical connections come before the control board. The board is the expensive assumption. The joints are the cheap check, and they sit where the weather gets at them.
What fixed it
We cleaned the corroded joints with contact cleaner and stripped the wire ends back to fresh copper. We then refitted them with new connectors so the contact was tight again. To slow future oxidation, we applied protective grease over the connection. The E6 error cleared on the next startup. We ran several start-stop cycles to confirm the signal held steady under load. No control board replacement was needed.
Outcome
The E6 error cleared once the outdoor wire connections were cleaned and refitted. The unit has run without a single communication fault since, and the homeowner avoided the cost of a new board.
What this case teaches us
A communication error often points to the wire, not the board
- An E6 code means the indoor and outdoor units have lost contact. That can be a corroded wire connection, not a failed board.
- Check the cheap, physical things first. Cleaning and refitting an outdoor connection costs far less than a control board.
- If a contractor is unsure of the brand, a second opinion can save the cost of a part you do not need.
Questions this case answers
York aircon keeps showing E6 and shutting off: what is the usual cause?
Is a communication error always a board replacement?
What does green oxidation on outdoor wire joints do to the signal?
How do I know whether the wire or the board is at fault?
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Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.