Error code · Professional Range

Monogram ZGP Range Code C4: Auxiliary relay board link

Medium · inspection needed

Code: C4
Appliance: Professional Range
Brand: Monogram
Warranty: 30-day workmanship

What C4 means

Monogram ZGP professional gas ranges, among them the ZGP486ND, report C4 when the oven control loses its link to the auxiliary relay board. This second relay board handles loads that the main relay board does not, such as certain fans, lights or the lockout. When the link drops, those loads cannot be controlled. The control stores C4, and the stored-code list is read by technicians in a test menu available briefly after power-up.

Common causes of C4

Harness between the control and the auxiliary relay board
Connector at either end not seated
Auxiliary relay board not answering
Control communication output

✓ One safe check you can try

1. Leave the oven controls off while you check the lights and fans. 2. Look at whether the oven lights and fans behave normally. 3. Try a simple bake and watch for the code. 4. If C4 returns, leave the oven off and call us.

! Why to stop there

The auxiliary board serves several loads, so what fails depends on the model
We check the harness and connectors before the board
We confirm which loads the board runs on your range before quoting a repair

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

→Same appliance

Other Professional Range codes

ProdMonogram ZGP Range Code Prod: Factory test mode CXMonogram ZGP Range Code CX: Communication error C1Monogram ZGP Range Code C1: Main relay board link C2Monogram ZGP Range Code C2: Upper temperature encoder C3Monogram ZGP Range Code C3: Upper mode encoder C5Monogram ZGP Range Code C5: Lower temperature encoder C6Monogram ZGP Range Code C6: Lower mode encoder SFMonogram ZGP Range Code SF: Special features menu

C4C4 questions

How is C4 different from C1?

C1 concerns the main relay board. C4 concerns the auxiliary board. Both are communication codes, but they involve different boards and may affect different parts of the oven.

What might stop working?

Loads that the auxiliary board switches, such as a fan, a light or a lock. We confirm which of those exist on your particular model during the visit, since it varies.

Is it safe to use the cooktop?

The cooktop burners run separately from the oven control on a gas range, but if you smell gas at any time, leave the house and call the gas utility from outside.

Book a visit

Still seeing C4?

A technician diagnoses it on site and gives you the price in writing before any work starts.

(713) 955-0955