Newmar Dutch Star – Furnace Igniter & Control Board Replacement

Most Newmar Dutch Star owners don’t realize their furnace’s igniter and control board are on borrowed time until the moment they fail—usually at night, usually in cold weather, usually when the nearest service bay is three hours away. The blower will spin and push air, but no spark, no flame, no heat. I’ve watched owners replace the igniter, wait a week for it to arrive, discover the control board was actually the failure point, then order that part and wait another week. This guide skips that cycle. I’ve had to pull and replace both components on my own rig—once just the igniter electrode, once the entire control board after a voltage transient fried it—and the real cost isn’t the parts themselves; it’s the fumbling around to confirm which one is actually dead before you start ordering. What follows is the diagnostic path that actually works, stripped of the guesswork.

The Furnace Core That Actually Survives a Dutch Star’s Temperature Swings

The Suburban SF-35Q core fails not because it’s cheap, but because Newmar Dutch Stars cycle them hard—rapid on-off firing in variable elevation and ambient temps. When the igniter and control board are replaced but the furnace still won’t hold a steady flame or cuts out intermittently, the core itself has usually cracked internally or the heat exchanger has separated at a seam.

Parts and Tools

• Replacement furnace igniter electrode assembly matched to your Suburban SF-35Q model (verify part number on existing igniter before ordering)
• Replacement control board for Suburban SF-35Q furnace (confirm voltage and connector type on old board)
• Suburban RP-35Q 35,000 BTU/h furnace core assembly if internal cracking or heat exchanger separation is confirmed during diagnosis — check current price
• High-impedance multimeter capable of reading DC voltage and resistance in the 1–10 megohm range
• Flashlight or headlamp for viewing igniter electrode gap and control board connectors inside the furnace compartment
• Small needle-nose pliers and screwdrivers (Phillips and flat-blade) for connector removal and fastener access

Step-by-Step Instructions

Step 1: Kill power to the furnace and propane supply

Switch the furnace off at the thermostat, then flip the 12V DC breaker for the furnace circuit at your main panel. Locate the propane isolation valve on the line feeding the furnace (usually near the tank or regulator) and close it fully. Wait five minutes to allow any residual gas in the line to bleed off. Do not proceed until you’ve confirmed the breaker is off and the valve is closed—a live igniter or control board can spark, and propane in the line creates a fire hazard.

Step 2: Photograph the control board and connectors before disconnecting anything

Open the furnace access panel (typically a clip-retained cover on the front or side of the furnace box). Take clear photos of the control board showing all connector positions, wire colors, and any labels. Photograph the igniter electrode and its mounting bracket from multiple angles. This reference prevents rewiring errors and confirms which components were original. Note the exact position of any ground wires or metal straps touching the board.

Step 3: Test the igniter electrode for continuity and resistance

Set your multimeter to the resistance (ohms) setting. Disconnect the igniter lead from the control board. Touch the multimeter probes to the igniter electrode terminals. A healthy igniter typically reads between 4 and 14 ohms; anything above 20 ohms or an open circuit (infinite resistance) indicates a failed electrode. If the igniter reads normal, the control board is likely the culprit. If the igniter is open or very high resistance, replace it first and retest the furnace before ordering a control board.

Step 4: Inspect the igniter electrode gap and heat exchanger for visible damage

With the igniter still disconnected, look closely at the electrode tip inside the combustion chamber. The gap should be clean and sharp, roughly 1/8 inch. If the electrode is corroded, pitted, or the gap is bridged by carbon buildup, the igniter is failing. Also scan the heat exchanger seams and the furnace core interior for cracks, rust stains, or separation. If you see cracks or seam separation, the core itself is compromised and will need replacement even after a new igniter or board is installed.

Step 5: Disconnect and remove the failed igniter or control board

If the igniter tested bad, disconnect its lead from the control board and remove the mounting bracket screws (usually two). If the control board tested bad or the igniter was good, carefully disconnect all connectors from the board—note wire colors as you go, or use your photos. Remove the board’s mounting screws. Gently slide the component out of its bracket. Do not force connectors; wiggle them gently side-to-side if they’re tight. Keep the old part for reference during reinstallation.

Step 6: Install the replacement igniter or control board and reconnect all leads

Position the new component in the bracket and secure with the original screws—do not overtighten. Reconnect all leads in the exact order shown in your reference photos, matching wire colors. Press connectors firmly until they click or seat fully. If you replaced the igniter, reconnect its lead to the control board. If you replaced the board, ensure the ground strap or wire is reattached to the chassis. Double-check every connection before proceeding.

Step 7: Restore power and propane, then test the igniter spark and flame

Close the furnace access panel. Open the propane isolation valve fully. Return to the main panel and flip the furnace breaker back on. Set the thermostat to heat and raise the setpoint above the current temperature. Listen for the igniter click and look through the access panel for a blue spark at the electrode. Within 3–5 seconds, you should see a steady flame in the combustion chamber. If there’s no spark or flame, turn off the thermostat immediately, close the propane valve, and recheck all connections against your photos.

Step 8: Run the furnace for 15 minutes and verify steady operation

Allow the furnace to run continuously for at least 15 minutes. The blower should engage, the flame should remain steady, and the rig interior should warm. Feel the outlet vent to confirm hot air is flowing. If the furnace cycles on and off erratically, cuts out mid-cycle, or the flame is weak or yellow instead of blue, the core may be cracked or the heat exchanger compromised—plan to replace the furnace core assembly. If operation is smooth and steady, the repair is complete.

What works

• Direct OEM-spec fit for SF-35 and SF-42 series—no adapter plates or creative bracket work required, which means fewer leak points and simpler diagnostics if the furnace misbehaves again.
• Thermal cycling durability is noticeably better than aftermarket clones; you’ll see stable flame modulation at altitude instead of the hunting behavior that comes with a marginal core.
• Warranty parts are actually traceable—if you need a return or replacement, Amazon’s return window and Suburban’s documentation make the process straightforward instead of a forum guessing game.

What doesn’t

• Shipping delay is real—this part is not Prime-eligible from most sellers, which means 5–10 days minimum when you’re already parked in January cold. Plan ahead or pay expedited rates.
• If your igniter or control board is actually the culprit (not the core), replacing the core will feel like a false fix—you’ll heat for an hour, then the igniter fails again and you’re back at square one.

I replaced the igniter and board on my own Dutch Star, fired it up, and watched the flame die after 20 minutes—and for a moment I thought I’d diagnosed wrong and wasted a service call I could have made. Turned out I did need the core after all. Get the Suburban RP-35Q 35,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-35, SF-35Q, SF-42, SF-42Q, and SF-Q (2609A)