Trane Error Code 4: Open Limit Switch

LED Blink Pattern

How to Fix Trane Code 4

1. Step 1: Check for any visible damage or disconnections in the wiring around the limit switch.
2. Step 2: Ensure that the limit switch is securely fastened and not damaged.
3. Step 3: If you're comfortable doing so, inspect the wiring for any breaks or disconnections. If you're not sure, contact a professional HVAC technician.

How to Reset Trane Code 4

1. Turn off the furnace power switch, usually located on or near the unit.
2. Turn off the circuit breaker for the furnace. Wait 30 seconds.
3. Restore power at the breaker and flip the furnace switch back on.
4. Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.

Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.

What Does Trane Error Code 4 Mean?

An open limit switch error on your Trane HVAC system indicates that the system has detected an open circuit in the limit switch wiring. The limit switch is a safety device that prevents the furnace from overheating. When the system detects an open limit switch, it shuts down to prevent potential damage or safety hazards. This error is typically caused by a broken or disconnected wire in the limit switch circuit.

Common Causes

• Broken or disconnected limit switch wire
• Faulty limit switch
• Loose connection in the limit switch wiring

Diagnostic Steps

Replacement Parts

Related Codes on Same Models

Other codes that affect the same Trane model families as 4.