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Error code reference

GE Range Error Code C4

Communication fail with Aux

GE codesGE range codes

Communication fail with Aux. Relay Board.

First step from the service manual

Check harness first and then replace component indicated by Cx Error Code.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What C4 means on a GE range

The C4 error code on a GE range indicates a communication failure between the main control board and the auxiliary relay board. The auxiliary relay board is a secondary control component responsible for managing specific electrical outputs, such as relay-switched circuits that control burners, oven elements, or other high-voltage loads. When the main board cannot establish or maintain a valid communication signal with the auxiliary relay board, it flags the C4 fault and may restrict range operation to prevent unsafe conditions.

Communication between the main control board and the auxiliary relay board travels through a wiring harness that carries low-voltage data signals. The most common cause of this fault is a problem within that harness, including loose connectors, broken wires, or terminals that have corroded or backed out of their housings. Because the harness is the first point of failure in this communication path, inspecting it thoroughly before replacing any boards is the correct diagnostic sequence.

If the harness and its connectors are intact and show no signs of damage, the fault is likely internal to either the auxiliary relay board or the main control board itself. The auxiliary relay board is the more probable failed component when the harness checks out, since the C4 code points specifically to communication with that board. Replacing the component indicated by the Cx error series is the recommended corrective action once wiring has been ruled out.

Source: manufacturer service documentation.

Common causes of C4

  1. 01

    Loose or disconnected wiring harness connector

    Wiring / connection

    The harness connector linking the main board to the auxiliary relay board may have vibrated loose or was not fully seated. Inspect both ends of the harness for connectors that are not fully latched.

  2. 02

    Damaged or broken wiring harness

    Part replacement

    Wires in the harness can fray, burn, or break due to heat exposure or physical contact with moving parts. Look for any visible wire damage, scorching, or pinched sections along the harness route.

  3. 03

    Corroded or pushed-back terminals

    Wiring / connection

    Terminals inside the harness connectors can corrode from moisture or push back out of their housing, breaking the circuit. Carefully inspect each terminal pin for corrosion buildup or improper seating.

  4. 04

    Failed auxiliary relay board

    Part replacement

    If the harness and connectors are in good condition, the auxiliary relay board itself may have failed internally and can no longer respond to communication signals from the main board. The board will need to be replaced.

  5. 05

    Failed main control board

    Part replacement

    Less commonly, the main control board may have lost the ability to send communication signals to the auxiliary relay board. This is typically considered after the harness and auxiliary relay board have been checked.

See the test procedure for each cause

Frequently asked questions about C4

What does C4 mean on a GE range?
The C4 code on a GE range means the main control board has detected a communication failure with the auxiliary relay board. The auxiliary relay board manages relay-switched circuits for cooking functions, and when communication is lost, the range triggers this fault. The issue can stem from a faulty wiring harness, a bad connector, or a failed board.
Can I fix a C4 error on my GE range myself?
A knowledgeable DIYer can start by unplugging the range and inspecting the wiring harness and connectors between the main control board and the auxiliary relay board. If connectors are loose, reseating them may clear the fault. If the harness is damaged or a board needs replacement, the repair becomes more involved and may be better suited for a qualified technician.
Will resetting my GE range clear the C4 error code?
Unplugging the range for a few minutes and restoring power may temporarily clear the C4 code, but if an underlying wiring or board problem exists, the code will return. A reset alone does not repair a faulty harness connection or a failed auxiliary relay board, so the root cause still needs to be diagnosed and corrected.
Is it safe to use my GE range while it shows a C4 error?
A C4 error means the range has lost communication with a board that controls relay-switched cooking circuits, which can cause unpredictable operation of burners or oven elements. Continuing to use the range in this state is not recommended, as the relay board may not respond correctly to control commands. The range should be taken out of service until the fault is resolved.
How much does it cost to repair a C4 error on a GE range?
Repair costs vary depending on what component has failed. If the fix is simply reseating a loose connector, there may be no parts cost, though a service call fee typically applies and can range from around $75 to $150. If the auxiliary relay board or main control board requires replacement, parts can add anywhere from $100 to $350 or more to the total repair bill, depending on the specific model.

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