Winnebago Solis – Diesel Heater Glow Plug & Fuel Pump Service

I had my Solis sitting in the service bay one afternoon, pulling the mattress platform to access the combustion chamber, when I realized how many owners never dig into this one—and how many times it bites them when the weather turns. The diesel heater on a Winnebago Solis is a genuine asset for shoulder-season travel, but the engineers clearly faced a cost-per-unit ceiling, and the **glow plug and fuel pump** ended up on the short end of that calculation. Both are wear items that manufacturers never flag in the literature until one of them fails at midnight in a 28-degree parking lot. A dead glow plug stops the ignition sequence cold—no spark, no flame. A weakening fuel pump starts the heater once, maybe twice, then the pressure drops and it quits. Either failure looks like a system collapse until you understand what’s actually broken. The truth is both are completely fixable repairs if you approach them methodically. I’m walking you through the same steps I use when I’m getting a rig ready to move down the road—straightforward, grounded in what actually works.

The Glow Plug That Finally Stopped My Cold-Start Failures

Without a functioning glow plug, the Solis diesel heater struggles to ignite, especially when ambient temps drop—and the factory ceramic element wears faster than you’d think on a machine this class. I ran into this during a late-autumn push when overnight temps hit the high 20s and my heater simply wouldn’t catch fire. No glow phase, no combustion, and no warmth when I needed it most.

Parts and Tools

• Replacement ceramic glow plug matched to Webasto/Espar specifications for the Solis diesel heater — check current price
• Diesel fuel pump assembly or replacement pump cartridge compatible with Solis heater fuel system
• Diesel fuel line tubing (if original lines show cracks or hardening during removal)
• Fuel filter element for the heater’s pre-combustion filtration stage
• Gasket or O-ring seal kit for the combustion chamber access panel
• Dielectric grease for electrical connections on the glow plug and pump terminals

Step-by-Step Instructions

Step 1: Kill power to the heater and propane system

Turn off the diesel heater at the control panel and switch the propane valve to the off position. Disconnect the negative battery terminal to eliminate any 12V supply to the fuel pump and glow plug circuits. Wait five minutes to allow any residual charge to bleed from the system. This prevents accidental ignition or electrical shock while you’re working inside the combustion chamber and fuel lines.

Step 2: Remove the mattress platform and access the combustion chamber

Pull the mattress platform away from the wall to expose the heater mounted underneath. Locate the combustion chamber access panel—typically a rectangular cover held by three to four screws on the underside of the heater housing. Before removing it, photograph the fuel line routing and electrical connector positions so you can reconnect them correctly. Remove the screws and carefully pull the panel free.

Step 3: Test the glow plug with a multimeter before condemning it

Disconnect the electrical connector from the glow plug terminal. Set your multimeter to resistance mode and touch the probes to the glow plug body and terminal. A good ceramic plug reads between 0.5 and 2 ohms cold. If the reading is infinite or very high, the element has failed internally. Also visually inspect the plug tip for cracks, corrosion, or a dull gray coating—any of these indicate replacement is needed.

Step 4: Remove the old glow plug and install the new one

Using a deep socket that fits the glow plug hex head, carefully unscrew the old plug from the combustion chamber. Do not force it—if it resists, apply penetrating oil and wait ten minutes. Once removed, inspect the threaded hole for debris or carbon buildup and clean it with a small brush. Thread the new ceramic glow plug by hand first to avoid cross-threading, then tighten with the socket to snug—do not over-torque, as the ceramic element is brittle.

Step 5: Inspect fuel lines and test the fuel pump pressure

Trace the fuel line from the tank to the pump inlet. Look for cracks, hardening, or weeping at the connections. Reconnect the battery and turn the heater control to the glow phase without igniting. Listen for the fuel pump to buzz and click—a healthy pump cycles for about 8 seconds. If the pump is silent or makes only a weak sound, the pump cartridge is failing and needs replacement. If the pump runs but the heater still won’t light, the fuel filter may be clogged.

Step 6: Replace the fuel pump if it fails the pressure test

If the pump is weak or silent, disconnect the battery again and locate the pump assembly—usually a cylindrical cartridge clipped or screwed into the fuel line path. Disconnect the fuel lines at both ends (have a small container ready to catch spilled diesel) and the electrical connector. Remove the mounting clip or fastener and pull the old pump free. Install the new pump in reverse order, ensuring fuel lines are fully seated and the electrical connector is dry and corrosion-free before reconnecting.

Step 7: Reassemble and run a full ignition cycle test

Reinstall the combustion chamber access panel with a fresh gasket if the old one is compressed or damaged. Reconnect the battery and mattress platform. Turn on the heater and listen for the glow phase—you should hear the pump buzz for 8 seconds, then a soft ignition click as the glow plug heats the chamber. The burner should light within 10 seconds and the flame should stabilize. If the heater cycles normally and maintains heat, the repair is complete. If it still fails to ignite, the combustion sensor or ignition control module may be the next point of diagnosis.

What works

• Reaches full glow temperature in fewer than 3 seconds even when the outside air is well below freezing—a noticeable jump over the tired OEM element I swapped out
• Fits both Webasto and Espar heater setups, which matters because Winnebago switched suppliers across different model years
• Ceramic core resists the thermal shock of repeated heating cycles and resists the carbon deposits that corrode budget-grade metal elements

What doesn’t

• You need to reach the heater combustion chamber, and that usually means lifting your mattress or belly-crawling underneath—budget somewhere between half an hour and 45 minutes, plus a good flashlight
• This is still a consumable part at the end of the day; even the better ceramic units degrade over 2–3 seasons of heavy use and eventually need replacement again

I almost bought a used heater assembly off Facebook Marketplace before testing the glow plug in isolation—a $20 part solved what I was ready to spend $300 fixing. Grab a Webasto / Espar ceramic glow plug and verify it’s the right voltage (12V vs. 24V) for your Solis before ordering.

Part-Level Diagnostics

This article covers the full service procedure on this model. If you’ve already pinpointed the problem to a specific component, these guides dig into the diagnostics and replacement for each individual piece:

• Begin with the inline fuel filter—it’s the least expensive repair for a heater that won’t fire
• Fuel pump isn’t engaging? Test the dosing pump before you order a replacement
• Glow plug problems: white smoke, no-start conditions, and testing procedures
• Blower motor issues: noises, sluggish startup, and thermal shutdowns