Forest River Sunseeker – Furnace Igniter & Control Board Replacement

Let a Sunseeker furnace sit dormant through a cold snap with a failed igniter, and you won’t be thinking about the repair cost — you’ll be thinking about how fast hypothermia sets in inside a rig that can’t hold 50 degrees. That’s not hyperbole if you’re parked at elevation in January or anywhere the mercury regularly dips below freezing. I learned this the hard way at 9,000 feet in Colorado when my control board died mid-winter, and the gap between “furnace quit working” and “shelter becomes a survival problem” turned out to be about six hours. This guide walks through the igniter and control board replacement on the Suburban SF-series furnace the way it actually happens — the sequence I used to get heat flowing again, stripped of the dealership cushion-speak and focused on what you need to do when the thermometer is dropping and your family is already in jackets indoors.

The Igniter That Actually Survives Repeated Cold Starts on Suburban SF-Series Furnaces

The electrode igniter is the first thing to fail when you’re cycling your furnace at elevation or in sub-zero temps — it cracks from thermal stress, corrodes from moisture in the combustion chamber, or just stops arcing after a few hundred ignition attempts. When it goes, your furnace won’t light, and you’re troubleshooting in the dark at 3 AM trying to figure out if it’s the igniter, the control board, or a gas supply issue.

Parts and Tools

• Replacement igniter electrode with wire assembly matched to your Suburban SF-series model (SF-20, SF-25, SF-30, or SF-35) — check current price
• Replacement control board for your specific Suburban furnace model (verify part number against your existing board before ordering)
• Needle-nose pliers or tweezers for disconnecting small wire terminals inside the furnace cabinet
• Flashlight or headlamp for visibility inside the furnace compartment
• Multimeter set to voltage and continuity modes for testing igniter and control board function
• Small Phillips and flathead screwdrivers for removing cabinet panels and terminal screws

Step-by-Step Instructions

Step 1: Kill power to the furnace at the breaker

Locate your RV’s main electrical panel and switch off the breaker controlling the furnace circuit—typically labeled 120V or Furnace. Wait 30 seconds to allow any residual charge to bleed off. This prevents shock when you touch the control board or igniter terminals. Do not skip this step even if the furnace is already dead; the control board may still hold voltage.

Step 2: Photograph the wire connections before disconnecting anything

Open the furnace access panel (usually on the front or side of the cabinet) and take clear photos of every wire connected to the control board and igniter, including the color and terminal position. Use your phone’s zoom to capture the exact layout. This single photo will save you 30 minutes of guessing when you’re reassembling. Label the wires with tape if the connections are tight or unclear.

Step 3: Test the igniter for continuity and spark

Set your multimeter to continuity mode and touch the probes to the igniter’s wire terminals. A good igniter shows low resistance (typically under 10 ohms). If the meter shows open circuit (no beep), the igniter is dead. Visually inspect the ceramic probe for cracks or dark corrosion spots—these confirm failure. If the igniter tests good but the furnace still won’t light, the control board is likely the culprit.

Step 4: Disconnect and remove the old igniter

Using needle-nose pliers, gently pull the wire terminals straight out of their slots on the control board. Do not twist or yank sideways—these connectors break easily. Once the wires are free, locate the igniter’s mounting bracket (usually a single screw or clip holding it near the burner assembly) and remove it. Slide the old igniter out carefully, noting its exact position and angle relative to the burner.

Step 5: Install the new igniter in the correct position

Slide the new igniter into the mounting bracket, ensuring the ceramic probe sits at the same distance and angle as the original—typically 1/8 inch from the burner flame path. Secure the mounting bracket with its screw or clip. The probe must not touch the burner or any metal part of the combustion chamber. Reconnect the wire terminals to the control board, matching your reference photo exactly.

Step 6: Disconnect and replace the control board if needed

If the igniter tests good but the furnace still won’t light, the control board is the problem. Disconnect all wires from the board (photograph again), then unscrew the board from its mounting bracket. Install the new board in the same position and orientation, reconnect all wires in the exact order shown in your photo, and double-check each connection for a firm seat.

Step 7: Restore power and test the furnace

Switch the breaker back on and set your thermostat to heat mode with a target temperature 5 degrees above the current cabin temperature. Listen for the igniter clicking (a rapid ticking sound) followed by the burner igniting with a soft whoosh. The furnace should run for 30 seconds, then cycle off as the cabin warms. If it clicks but doesn’t light, check that the gas supply valve is open and the propane tank isn’t empty.

What works

• Direct fit on SF-20, SF-25, SF-30, and SF-35 models — no adapter hunting or modification needed, and the wire assembly is already terminated correctly.
• The ceramic probe holds up through repeated thermal cycling; you’ll actually see reliable spark across the gap on every ignition cycle instead of intermittent arcs that make you question your diagnostics.
• Replacement takes 20 minutes if you’ve killed the propane and 12-volt power — no special tools, just access to the combustion chamber and a wrench for the mounting bracket.

What doesn’t

• The wire insulation is thin and vulnerable to chafing if you don’t route it carefully during installation — one careless bundle against a sharp interior edge and you’re looking at a ground fault a month later.
• This is a replacement part, not a diagnostic tool — if your furnace still won’t light after swapping the igniter, you’ve got a control board or gas valve problem, and you’ll be back in the manual anyway.

I had one igniter arrive with a hairline crack in the ceramic that wasn’t visible until I held it up to a flashlight, which meant I nearly installed a dead part and would’ve spent another two days convincing myself the control board was the real culprit. 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)