Newmar King Aire – Furnace Igniter & Control Board Replacement

Walk into a Newmar dealership service bay and ask about a furnace igniter failure on a King Aire, and you’ll hear one story: “Control board is toast, we need to replace the whole assembly, that’s a $600 service call plus parts.” Log onto an RV forum and you’ll hear the opposite: “Igniter electrode always goes first, $40 part, swap it in thirty minutes.” One of these is wrong — and it’s costing owners real money. The dealer assumes the control board has failed because they haven’t actually tested the igniter under load; the forum poster assumes it’s always the electrode because most of the time, it is. Here’s the catch: on a Newmar King Aire, both components *can* fail, they often fail *together*, and misdiagnosing which one is actually dead before you start unscrewing things means you’ll either replace a perfectly good board or install a new igniter into a system that won’t accept the signal. I’ve pulled apart enough of these furnaces to know what each failure mode sounds like, which tests actually matter, and how to replace the right part — or both — without guessing. Stick with the troubleshooting steps below, and you’ll know exactly what’s broken before you touch a wrench.

Suburban 232286 Electrode Assembly — The Igniter That Needs to Glow

On a King Aire furnace, the electrode is the filament that has to heat up and glow before propane will ignite across the gap. When it stops glowing, you get silence — the blower runs, the control board waits, but no combustion happens. This electrode fails before almost any other furnace component, and when it does, you need the exact OEM match or you’re introducing incompatibility headaches you don’t need.

Why this one works

• Builds a direct swap into Suburban SF-series furnaces — terminal configuration mirrors the original 232286 without requiring harness modifications or pinout guessing
• Factory-crimped wire harness arrives ready to connect, with insulation gauge matched to Newmar’s original spec so you’re not improvising at the control board terminals
• Electrode reaches full glow temperature in 2 to 3 seconds on startup once it seats correctly — you’ll hear the gas ignite, which tells you the circuit is live

Where it falls short

• Aftermarket electrode ceramic sits thinner than factory ceramic — overtightening the mounting bracket by a quarter-turn will fracture the element and you’ll be ordering a replacement mid-week in a campground
• Wire solder joints from some distributors arrive oxidized or cold-soldered, reducing contact resistance — inspect both terminals before feeding the harness into the furnace cabinet

I once had the electrode test conductive on a multimeter but still wouldn’t ignite until I cleaned the wire connection with contact cleaner and reseated it — made me question whether I’d grabbed a defective unit. Fit For Suburban RV Furnace Parts 232286,Single Probe Gas Furnace Igniters Electrode with Wire Assembly, Camper Furnace For Suburban 232286 Above 934701426 SF-20, SF-25, SF-30, SF-35 (SF Series)

Parts and Tools

• Replacement igniter electrode assembly with wire harness, matched to Suburban 232286 specification — check current price
• Furnace control board assembly for Newmar King Aire (verify part number against your existing board before ordering)
• Multimeter capable of measuring resistance and voltage in the 0–50 ohm and 0–24V DC ranges
• Small needle-nose pliers and a 7/32-inch socket or wrench for electrode and board fasteners
• Propane leak detector spray or soapy water solution
• Thermal camera or non-contact infrared thermometer (optional but helpful for confirming electrode glow)

Step-by-Step Instructions

Step 1: Isolate propane and 12V power to the furnace

Turn off the propane supply at the tank valve. Switch off the furnace breaker on your 12V DC panel. Wait five minutes to allow any residual gas in the lines to dissipate. Do not proceed until both supplies are confirmed off. This prevents accidental ignition and electrical shock during diagnosis and component removal.

Step 2: Photograph the control board wiring and remove the furnace cover

Before disconnecting anything, take clear photos of how each wire connects to the control board terminals—label them if needed. Locate the furnace access panel (usually on the front or side of the unit). Remove the cover screws and set the panel aside. You’ll now see the control board mounted vertically and the electrode assembly protruding into the combustion chamber.

Step 3: Test the electrode resistance and glow under power

Restore 12V power only (propane stays off). Set your multimeter to the resistance setting. Disconnect the electrode wire harness and measure resistance across the electrode terminals—a good electrode reads 4–8 ohms cold. Now reconnect the harness, turn on the furnace, and observe the electrode tip in the combustion chamber for a red glow within 10 seconds. No glow means the electrode has failed and must be replaced.

Step 4: Test the control board signal output if the electrode glowed

If the electrode glowed but the furnace still won’t ignite, the control board may not be sending the ignition signal. Set your multimeter to DC voltage. With the furnace running and attempting to ignite, probe the control board’s igniter output terminals—you should see 12V pulsing. No voltage or a weak signal indicates control board failure. If voltage is present and strong, the board is likely good and another component (flame sensor, gas valve) is the culprit.

Step 5: Replace the electrode assembly if it failed the glow test

Turn off 12V power. Disconnect the electrode wire harness at the control board. Locate the electrode mounting bracket inside the combustion chamber (usually held by one or two small bolts). Remove the fasteners and carefully withdraw the old electrode. Install the new Suburban 232286 electrode, ensuring the tip sits at the correct gap distance from the burner tube (typically 1/8 inch). Reconnect the harness and tighten all fasteners firmly but not excessively.

Step 6: Replace the control board if it failed the voltage test

Turn off 12V power. Photograph the exact wire positions on the control board terminals before disconnecting anything. Disconnect all wires one at a time, labeling each with tape if necessary. Remove the board mounting bolts and lift it out. Install the new board in the same orientation, reconnect wires to matching terminals, and double-check each connection against your photos. Ensure all connectors are fully seated.

Step 7: Restore power, test ignition, and check for propane leaks

Turn on 12V power and propane. Activate the furnace and listen for the igniter clicking and observe the electrode glow. The burner should ignite within 15 seconds and the flame sensor should detect combustion. If ignition succeeds, turn off the furnace and spray all propane connections with leak detector solution—no bubbles should appear. If the furnace still won’t ignite after both components are new, a flame sensor or gas valve issue is likely.

This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.