Newmar Bay Star Sport – Furnace Igniter & Control Board Replacement

Newmar doesn’t publish a troubleshooting flowchart for furnace failures, and dealer service advisors rarely volunteer that most no-heat situations in a Bay Star Sport come down to two specific, owner-replaceable parts. You won’t find this in the owner’s manual either — what you get is a schematic diagram and a parts list, but no step-by-step on which component to suspect first or how to rule out the other one. When you’re full-timing and the furnace quits mid-season, downtime costs money, and waiting for a service appointment costs comfort. The reality is straightforward: a failed igniter electrode or a defective control board handles most of these callouts — and both are accessible to anyone with a basic socket set and the willingness to spend an afternoon in the furnace compartment. This post covers exactly what I found when I dug into ours, how I confirmed which part was actually bad, and the step-by-step to swap them out without a dealer’s markup or a multi-week service queue.

The Igniter That Actually Fires When Everything Else Tests Fine

The igniter is the first thing that fails on a Suburban SF-series furnace, and it’s the hardest to diagnose because you can have 12V at the control board, gas flow confirmed, and a blower that runs — but the furnace still won’t light. A dead electrode is invisible until you pull it out and see the ceramic cracked or the wire corroded.

Parts and Tools

• Replacement igniter electrode with wire assembly, pre-gapped and matched to Suburban SF-series furnace specifications — check current price
• Replacement control board for Suburban SF-series furnace, matched to your model year and voltage configuration
• Socket set with 1/4-inch and 3/8-inch sockets to access furnace compartment fasteners
• Multimeter capable of measuring DC voltage and continuity
• Flashlight or headlamp for visibility inside the furnace compartment
• Needle-nose pliers for disconnecting wire terminals from the control board
• Camera or phone to photograph wire connections and terminal positions before disconnection

Step-by-Step Instructions

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

Turn off the propane supply at the tank or inline shutoff valve. Switch off the furnace breaker on the main panel or disconnect the 12V battery if your rig uses a dedicated furnace circuit. Wait five minutes to allow any residual gas to clear. This prevents accidental ignition during diagnosis and component removal. Check that the furnace blower does not run when you attempt to activate the thermostat — this confirms power is truly isolated.

Step 2: Access the furnace compartment and locate the control board

Open the exterior furnace access panel, typically located on the street side of the Bay Star Sport near the floor line. Remove the cover screws and set them aside in a labeled container. Photograph the entire interior layout, including wire routing and terminal connections on the control board. The control board is the rectangular module mounted vertically on the furnace housing; the igniter electrode protrudes from the combustion chamber directly below or beside it. Note the exact position of all wires before touching anything.

Step 3: Test igniter continuity and electrode condition

Set your multimeter to the continuity or resistance setting. Locate the two wire terminals on the igniter electrode assembly where they connect to the control board. Disconnect one terminal and probe across the electrode wires — a good igniter shows low resistance (typically under 10 ohms). If the reading is infinite or very high, the electrode is open internally. Visually inspect the ceramic insulator around the electrode tip for cracks or discoloration. A cracked or corroded electrode confirms failure and justifies replacement.

Step 4: Remove the failed igniter electrode

Using needle-nose pliers, carefully disconnect both wire terminals from the control board, noting their positions. Remove the mounting bracket or retaining clip holding the electrode assembly to the furnace housing — typically one or two small bolts. Gently pull the electrode straight out of the combustion chamber. Do not force it; if resistance is felt, check for a second fastener. Keep the old electrode for comparison when installing the new one to confirm proper fit and gap.

Step 5: Install the replacement igniter electrode

Insert the new electrode assembly into the combustion chamber opening, aligning it with the mounting holes. Secure it with the original bolts, tightened firmly but not over-torqued — hand-tight plus a quarter turn is sufficient. Reconnect the two wire terminals to the control board in the exact positions documented in your photograph. Ensure each terminal is fully seated and does not rock when gently tugged. The electrode should sit at the same depth and angle as the original.

Step 6: Test furnace operation and verify ignition

Restore 12V power and propane supply. Set the thermostat to heat mode and raise the setpoint above the current temperature. Listen for the blower to start and watch for the igniter to glow orange-red within 10 seconds. You should hear a soft ignition click followed by the main burner flame appearing in the combustion chamber window. Allow the furnace to run for two minutes, then cycle it off and back on to confirm consistent ignition. If the furnace fails to light, turn off power and propane immediately and proceed to control board diagnosis.

Step 7: Diagnose and replace the control board if igniter replacement did not restore heat

If the new electrode glows but the furnace does not ignite, or if the electrode does not glow at all, the control board is likely defective. Isolate power and propane again. Photograph all wire connections on the control board, labeling each terminal with tape if necessary. Disconnect all wires using needle-nose pliers. Remove the mounting bolts securing the board to the furnace housing. Install the replacement board in the same orientation, reconnect all wires to their original terminals, and restore power. Test ignition as described in the previous step.

Step 8: Verify sustained operation and close the access panel

Run the furnace through three complete heat cycles, allowing it to reach full temperature and cycle off naturally each time. Check that the blower starts smoothly, the igniter glows consistently, and the burner flame is steady and blue (not yellow or orange). Feel the warm air exiting the vents. Once satisfied, close the furnace access panel and secure all cover screws. Restore the exterior trim and test the thermostat from inside the rig to confirm normal operation.

What works

• Drop-in fit for SF-35, SF-42, and SF-35Q models — you won’t spend an hour figuring out if this is the right part once you pull the old one out.
• The electrode wire assembly is pre-gapped and ready to seat; you’re not hunting for the exact spacing or crimping new connectors in a cramped furnace compartment.
• Furnace fires on first try after installation — no guessing whether you need to adjust air shutter or second-guess the control board.

What doesn’t

• You have to pull the furnace shroud and access panel to confirm the old igniter is actually the problem — there’s no shortcut diagnosis without seeing the electrode itself.
• Aftermarket versions sometimes have slightly looser connector tolerances than OEM, which means you may need to crimp the spade terminals tighter to avoid intermittent no-fire conditions.

I ordered this part convinced it was the control board causing the trouble, and had the igniter half-installed before I realized the ceramic was visibly fractured — the board was innocent the whole time. 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)