You tested your generator — or the power went out and it didn’t kick on automatically — and now it won’t start. That’s a stressful situation, especially in the middle of a North Texas ice storm or summer heat wave.
Most standby generator failures have a handful of common causes. This article walks through them so you can identify what’s happening and decide whether it’s something you can check yourself or whether you need a technician on-site.
Important note: this article is for whole-home standby generators (Generac, Kohler, Champion, and similar permanently installed units). Portable generator issues are different and aren’t covered here.
If your generator isn’t starting and you need help now, call HomeSafe at (817) 439-9009.
The Most Common Reasons a Standby Generator Won’t Start
1. Dead or Weak Battery
The most common cause of a standby generator that won’t crank is a failed battery. Standby generators use a 12-volt battery (similar to a car battery) to power the starter motor and the generator’s control board. If the battery voltage drops below a usable level, the unit won’t start — even if everything else is working perfectly.
What to look for:
- The control panel is dark or shows a battery fault code
- The unit attempts to crank but turns over slowly
- The unit makes no sound at all when commanded to start
Battery failure is especially common when:
- The generator hasn’t been exercised (run) regularly
- The battery is more than 3–5 years old
- The unit sat unused through a long period of moderate weather when it wasn’t needed
What to do: Check for a fault code on the control panel display. If it shows a low-battery or battery fault, call a technician to test and replace the battery. A battery replacement is a straightforward service call.
2. Low Oil — Oil Pressure Sensor Shutoff
Standby generators are equipped with an oil pressure sensor that shuts the unit down (or prevents it from starting) if oil pressure falls below a safe level. This is a protection feature — running a generator without adequate oil causes catastrophic engine damage.
What triggers it:
- Oil that’s overdue for a change has degraded and may not hold adequate pressure
- Oil level has dropped due to normal consumption between service intervals
- A leak has reduced the oil supply
What to do: Check the oil level dipstick. If it’s low, top it off with the correct oil type (consult your owner’s manual or the generator’s spec label). Attempt to restart. If it starts, schedule a service visit to determine why the oil level dropped — and to perform any overdue maintenance.
If the oil level is fine but the unit still won’t start and shows an oil pressure fault, the sensor itself may have failed — a technician will need to diagnose this.
3. Transfer Switch Fault
The automatic transfer switch (ATS) is the component that monitors grid power and tells the generator to start when an outage is detected. If the ATS develops a fault — loose connection, failed contactor, wiring issue — the generator may not receive the start command at all, or may start but fail to connect your home to generator power.
Signs this might be the issue:
- The generator does start when you manually trigger it from the control panel, but your home never switches over to generator power
- The control panel shows an ATS or transfer switch fault code
- The unit runs but the lights don’t come on
This requires a technician. Transfer switch diagnostics involve live electrical components and should not be attempted by a homeowner.
4. Exercise Mode / Maintenance Mode Active
Most standby generators are programmed to run a short weekly exercise cycle (typically 20–30 minutes) to keep the engine lubricated and the battery charged. If yours is in exercise mode, it will start on schedule but won’t transfer your home’s load to generator power — by design.
Similarly, some generators have a manual “maintenance mode” that prevents automatic start during scheduled service work. If someone switched the unit to maintenance mode, it won’t respond to a grid outage.
What to do: Check the control panel settings. If exercise or maintenance mode is active, consult your owner’s manual on how to return the unit to automatic mode.
5. Fault Code from a Previous Issue
Generac, Kohler, and Champion generators store fault codes when they detect a problem. If the generator stopped during a previous run due to a fault — overspeed, overheating, low coolant, etc. — it may lock itself out and refuse to restart until the fault is cleared.
What to do: Check the control panel for a displayed fault code. Write it down. Call HomeSafe and give us the code — we can often tell you what it means and whether it’s something you can reset yourself or needs a technician.
6. Fuel Supply Issue
If your generator runs on natural gas, check that:
- Other gas appliances in your home (stove, furnace) are working — if they’re not, the issue may be with your gas supply, not the generator
- The gas shut-off valve on the line feeding the generator is fully open
If you’re on propane, check the tank level. A nearly empty tank won’t supply adequate pressure to start the generator.
What to Check Before You Call
Quick self-check list — in order:
- Look at the control panel. Is it powered on? Does it show a fault code?
- Check the transfer switch position: is it set to AUTO?
- Verify the unit is not in exercise or maintenance mode
- Check the oil dipstick
- For gas: verify other gas appliances are working
- For propane: check tank level
- Attempt a manual start from the control panel (refer to your owner’s manual for how to do this safely)
If the unit starts manually but doesn’t respond to outages, the issue is likely the transfer switch or its wiring. If it won’t start at all — manually or automatically — and no obvious fuel/oil issue is present, it’s time to call a technician.
When to Call a Technician Immediately
Call HomeSafe right away if:
- The generator is making unusual sounds (grinding, knocking, high-pitched whining)
- You smell gas near the unit
- There is visible damage to the unit, wiring, or pad
- The control panel shows an alarm you don’t recognize
- The unit ran during a recent outage and then stopped mid-outage
- You’ve had a recent ice storm, flooding, or other weather event and the unit may have been exposed to water or debris
Don’t attempt to reset faults or perform electrical work on the generator yourself. Standby generators connect directly to your home’s main electrical panel — this is licensed electrical territory.
Why This Keeps Happening — and How to Prevent It
Most standby generator startup failures are preventable with annual maintenance. A professional service visit covers:
- Oil and filter change
- Spark plug inspection and replacement
- Air filter check
- Battery test and load test
- Fuel system inspection
- Transfer switch testing
- Control board diagnostic scan
- Full exercise test under load
HomeSafe offers annual generator maintenance plans for DFW homeowners. A generator that gets serviced every 12 months — regardless of how many hours it’s run — is far less likely to fail when you actually need it.
If this is the second time you’ve had a startup problem, it’s worth asking: when was it last serviced?
HomeSafe Generator Service — DFW
We service all major residential standby generator brands including Generac, Kohler, and Champion across Tarrant, Denton, Collin, and Dallas counties. As a Generac PowerPro Elite+ dealer, we carry most common replacement parts in stock — which means faster repairs and fewer “waiting on parts” delays.
Generator Won’t Start? We Can Help Today
Don’t wait for the next storm to find out if your generator is reliable. Call HomeSafe and we’ll diagnose the issue, explain what we find, and give you a straightforward repair quote.