mypros+
Error code reference

Lennox HVAC Error Code 302

The R to O jumper was not removed on the air-handler control board.

Lennox codesLennox hvac codes
Avg. service call
$285
National average. Trip fee plus diagnostic plus labor. Before parts.
MyPros+ 3-day pass
$9.95
Same diagnostic steps, on your phone. Start now.
You keep in your pocket
~$275
Even before you buy the part.
Skip the service call. Fix it yourself.
Full procedure unlocks instantly.
Get Started

What the 302 error code actually means

Your Lennox air handler has a small wire connection on its circuit board that needs to be removed because your outdoor unit and indoor unit use different communication systems. This connection was not removed during installation, which is causing the system to detect a conflict and display this error. Once a technician cuts or removes that small jumper wire, the error will go away and the system will work normally.

Diagnostic procedure

The full 302 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
Cut/remove R to O jumper. Applicable with non-communicating outdoor unit with communicating indoor unit. The fault clears after the R to O jumper is cut/removed.
Unlock with pass
Unlock with pass
Unlock with pass
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
Unlock 302 procedure $9.95

Or subscribe: $29/month for unlimited access to all codes plus Max AI diagnostics.

Most common causes of 302

Ranked by how often they cause this code
  1. 1Jumper not removed during initial installation
  2. 2Control board replacement without reconfiguring jumper
  3. 3Incorrect system pairing documentation followed
  4. 4Jumper partially cut but still making contact

Most DIYers save hundreds by diagnosing before ordering parts.

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass

Questions people ask about 302

What does 302 mean on a Lennox hvac?
Error code 302 means the R to O jumper on the air-handler control board was not removed. This fault applies specifically when a communicating indoor air handler is paired with a non-communicating outdoor unit. The jumper creates an unintended signal conflict on the control board. Cutting or removing the jumper clears the fault.
Will resetting the system clear error code 302?
No, simply resetting power to the system will not clear error code 302. The fault will return immediately because the underlying cause, the R to O jumper still being in place, has not been addressed. The error only clears after the jumper is physically cut or removed from the control board.
How much does it cost to fix Lennox error code 302?
Because no replacement parts are needed, the cost is limited to labor for a service call. Depending on your location and the HVAC contractor, a diagnostic and correction visit typically ranges from $75 to $200. If the fault appears immediately after a new installation, the installing contractor should correct it at no additional charge as part of their setup responsibilities.
How do I fix error code 302 on my Lennox system?
The fix is to locate and cut or remove the R to O jumper on the air-handler control board. This is a configuration step, not a parts replacement. Once the jumper is fully removed, the fault clears automatically without needing to manually reset the system. A qualified HVAC technician should perform this task to avoid damaging the control board.
Is error code 302 on a Lennox system a safety issue?
Error code 302 is a configuration fault, not a safety hazard. It does not indicate a refrigerant leak, electrical short, or component failure. However, the system may not operate correctly or at all while this fault is active, so it should be corrected promptly to restore proper heating and cooling function.

Related Lennox hvac error codes

All Lennox hvac codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass