Top Signs Your Diesel Heater Needs Servicing
Why Pay Attention to Heater Health?
Whether you’re a trucker parked overnight, a van lifer in the mountains, an RVer on the road, or a boater braving chilly mornings, your heater isn’t just about comfort — it’s about safety. Spotting issues early saves you from cold nights, costly breakdowns, and risky failures.
Here are the top signs your diesel heater is asking for servicing (before it quits on you).
1. Heater Won’t Start (or Struggles to Turn On)
The clearest sign something’s wrong: you press start… and nothing happens. Or it sputters, smokes, then shuts down.
Common causes:
- Clogged glow plug or carbon buildup in the combustion chamber
- Weak fuel pump or air bubbles in the fuel line
- Voltage drops from thin harness wiring or weak batteries
- Inadequate power supply → glow pin can’t fire, heater resets itself
- Huge clouds of white smoke = combustion failure → heater needs immediate maintenance
👉 If your power supply checks out but the heater still fails, servicing is the next step.
2. Weak or Reduced Heat Output
The heater runs, but you’re still shivering. Often caused by carbon buildup inside the heat exchanger or combustion chamber, reducing heat transfer.
Solution: Professional cleaning or part replacement to restore full heating power.
3. Strange Noises
A healthy heater should hum quietly. If you hear grinding, rattling, or explosive pops, it’s time to act.
Possible issues:
- Worn blower motor or bearings
- Coolant or fuel leaks where they don’t belong
- Failing internal seals
👉 Noise is your heater’s way of crying for help — don’t ignore it.
4. Error Codes on the Controller
Most modern heaters, including Autoterm units, display fault codes when something isn’t right.
Common ones include:
- Code 01 – Overheated heat exchanger
- Code 02 – Intake temperature too high
- Code 10/11/13 – Blower motor, glow plug, or sensor issues
👉 View the full Autoterm error code table here.
Don’t just reset and restart — the system is telling you something important.
5. Heater Shuts Off Unexpectedly
If your heater starts fine but cuts out:
- Instant shutdown (black thermostat screen) → power supply issue
- Normal shutdown cycle, then off → flame out caused by carbon buildup, fuel starvation, or low voltage
Consistent flame outs = your heater needs servicing before it leaves you in the cold.
6. Smells or Smoke from the Exhaust
Excessive smoke or strong fuel smell means poor combustion — often due to fuel supply problems, airflow issues, or carbon buildup.
Critical safety warning:
- If exhaust gases seep inside the cabin, shut the heater off immediately.
- This usually means failed gaskets inside the unit, which must be replaced before using the heater again.
Why Regular Service Matters
Even if everything seems fine, annual maintenance is smart — especially before winter.
Best practice: Run your heater at full power for 15 minutes once a month (even in summer). This burns off carbon and moisture, keeping internals clean.
A proper service may include:
- Cleaning or replacing the heat exchanger
- Checking gaskets & combustion chamber
- Inspecting or replacing the fuel pump
- Testing blower motor & sensors
- Reviewing wiring and connections
👉 Catching small issues early keeps your heater reliable, efficient, and safe.
Keep It Running Safe & Warm with General Components
At General Components, we specialize in heaters built for trucks, RVs, vans, and boats. We also stock all the spare parts you might need, backed by a 2-year warranty (1-year marine/off-road).
Not sure what’s wrong? Our team is here to help — from fault code troubleshooting to parts replacement, we’ll guide you through the best fix for your system.
👉 Don’t wait for a cold failure. Shop heaters & parts here — and stay warm wherever your journey takes you.
