Generac Generator Weekly Test Not Working: Why It Fails & How To Troubleshoot
Updated: February 1, 2026
If your Generac generator weekly test is not working, don’t panic. On most Guardian/home standby units, it’s usually one of four things: schedule settings, battery/charger issues, low oil, or an active warning code. This guide will help you identify the problem quickly.
- Confirm the generator is in AUTO mode
- Check the controller for any message or error code (take a photo)
- Verify the exercise schedule (day/time) and controller’s clock (DST can throw it off)
- If it started after an outage, wait until power stabilizes and check the next scheduled run
Related guides:
Charger Missing AC (Code 2780) |
Red light meaning |
How to reset after oil change
Contents
- 1 Quick Diagnosis: Why Is My Weekly Test Not Working?
- 2 Common Error Codes That Stop Weekly Tests
- 3 Most Common Causes (Detailed)
- 4 How to Reset Your Generac Generator
- 5 When to Call a Professional
- 6 Generac Indicator Light Meanings
- 7 Note About Portable Generators
- 8 Maintenance Schedule to Prevent Issues
- 9 Conclusion
- 9.1 What should I check first if my Generac weekly test isn’t running?
- 9.2 What does “Generac weekly test failed” mean?
- 9.3 Can a weak battery stop the Generac weekly exercise?
- 9.4 How do I manually run a Generac weekly test?
- 9.5 What battery does a Generac Guardian need?
- 9.6 What oil should I use in my Generac generator?
- 9.7 How often should Generac generators run their weekly test?
- 9.8 What does error code 1100 mean on Generac?
Quick Diagnosis: Why Is My Weekly Test Not Working?
| What You See | Most Likely Cause | Quick Check | Solution |
|---|---|---|---|
| Never starts at scheduled time | Schedule/time/date wrong OR not in AUTO | Check AUTO mode, exercise day/time, controller clock | Fix settings, wait for next run |
| Tries to start, then stops | Weak battery | Look for “Inspect Battery” warning; check battery age | Replace if 3-4+ years old |
| Displays error code | Active alarm stopped exercise | Take photo of code/message | Follow code guidance; call tech if it returns |
| Started after power outage | Utility/charger/controller issue | Note timing; check for charger warnings | Wait for power to stabilize; schedule service if persistent |
| Runs but shuts off early | Low oil or overheat protection | Check oil level (safe, no panels needed) | Top off oil; if it continues, call service |
Common Error Codes That Stop Weekly Tests
| Code | Message | Why It Stops Weekly Test | What to Do |
|---|---|---|---|
| 1505 | Inspect Battery | Battery too weak to crank engine | Check age; replace if 3-4+ years |
| 1100 | Overcrank | Engine failed to start after multiple tries | Check battery, then fuel supply |
| 1300 | Underspeed | Engine not reaching proper RPM | Could be fuel or engine issue; call service |
| 1400 | Overspeed | Engine running too fast | Call service |
| 1501/1511 | RPM Sense Loss | Controller can’t read engine speed | Call service |
| 1600 | Low Oil Pressure | Safety shutdown | Check oil level first; if OK, call service |
| 1800 | High Engine Temp | Overheat protection activated | Check for blocked airflow; call service |
| 2780 | Charger Missing AC | Battery charger not getting power | See our Charger Missing AC guide |
Pro Tip: Always take a photo of error codes. This saves time when calling for service.
Most Common Causes (Detailed)
1. Battery Problems (Most Common)
The weekly exercise is essentially a “mini start-up.” If your battery is weak, the test may:
- Skip entirely
- Start and immediately stop
- Show “Inspect Battery” warning
- Fail with Overcrank (1100) code
Signs of a weak battery:
- Battery is 3-4+ years old
- Slow cranking sounds
- Voltage below 12.5V at rest
- Visible corrosion or swelling
Recommended replacement: Most air-cooled Guardian units use a 12V Group 26R battery (AGM). Confirm 26R vs 26 terminal orientation before buying.
Keep it charged: A Generac OEM charger cord helps maintain charge between runs.
2. Schedule or Clock Settings
Simple but often overlooked:
- Not in AUTO: Generator must be in AUTO mode for scheduled tests
- Wrong day/time: Verify the exercise schedule matches your expectations
- Clock off: Daylight Saving Time changes or power interruptions can throw off the controller clock
- Timezone: Ensure controller timezone matches your location
3. Low Oil Level
Generac generators have low-oil protection. If oil is low, the weekly test may fail or stop early.
How to check oil (safe, no electrical work needed):
- Press OFF on the controller
- Wait 5-10 minutes for the engine to cool
- Open the lid and locate the dipstick
- Remove, wipe, reinsert, and check level
- Add 5W-30 synthetic oil if between ADD and FULL marks
- Return to AUTO mode
4. Charger/AC Feed Issues
If you see “Charger Missing AC” (Code 2780), the battery charger isn’t getting power from the transfer switch. This is often related to outages and typically needs a technician. See our complete guide: Charger Missing AC Explained
5. Fuel Supply Problems
For natural gas or propane units:
- Error code 1100 may indicate fuel issues
- Ensure gas valve is ON
- Check propane tank level if applicable
- If fuel is OK but problems persist, call service
How to Reset Your Generac Generator
If the weekly test failed and you want to try again:
- Press OFF on the control panel
- Wait 30 seconds
- Press MANUAL to run a 5-minute test
- Observe: Does it start and run smoothly?
- Press AUTO to return to normal operation
If it still fails: Note any error codes, check oil level, and verify battery condition. If problems persist, schedule professional service.
When to Call a Professional
Contact a Generac-certified technician if:
- Same error code returns after reset
- Red alarm light appears
- Multiple warnings display simultaneously
- Battery replaced recently but problems continue
- Any issue involving transfer switch, wiring, or electrical panels
- Generator won’t start during an actual outage
- Battery load test and charging system
- T1 circuit and transfer switch connections
- Fuel system pressure and flow
- Sensor calibration (oil pressure, RPM, temperature)
- Control board diagnostics
Generac Indicator Light Meanings
| Light | Status | Meaning |
|---|---|---|
| Green | Solid | Ready, in AUTO mode |
| Green | Flashing | Running (exercising or powering load) |
| Yellow | Solid/Flashing | Warning/maintenance needed |
| Red | Solid/Flashing | Alarm/fault – needs attention |
For complete light explanations, see: Generac Red Light On: Complete Guide
Note About Portable Generators
This guide covers Generac Guardian/home standby generators with automatic weekly exercise. If you have a portable generator, troubleshooting is different (spark plug, carburetor, manual fuel system). Portable units don’t have automatic weekly tests.
Maintenance Schedule to Prevent Issues
| Interval | Task | Who |
|---|---|---|
| Weekly | Check controller for warnings (visual) | Owner |
| Monthly | Check oil level | Owner |
| Every 6 months | Visual inspection, clean debris | Owner |
| Annually | Full service (oil change, filters, spark plugs, battery test) | Technician |
| Every 3-4 years | Battery replacement (proactive) | Owner/Tech |
Essential Maintenance Supplies
Keep these items on hand to ensure your generator is always ready:
- Fuel Stabilizer: STA-BIL Fuel Stabilizer keeps gas fresh for up to 24 months and prevents most fuel-related starting problems.
- Generator Oil: Briggs & Stratton 10W-30 Synthetic Oil is the recommended oil for most generators. Low oil is the #1 reason generators fail during emergencies.
- Battery Maintainer: A Battery Tender Junior keeps your generator’s battery at optimal charge between weekly tests.
Conclusion
When your Generac generator weekly test is not working, start with the basics: check AUTO mode, verify schedule settings, and look for error codes. Battery and oil issues cause most failures and are relatively easy to address. For anything involving electrical systems, transfer switches, or persistent error codes, call a qualified technician.
Remember: The weekly test exists to ensure your generator will work when you actually need it. Don’t ignore failed tests, they’re warning you about potential problems before an emergency.
What should I check first if my Generac weekly test isn’t running?
Confirm AUTO mode, check the controller for any message or error code, and verify the exercise schedule and controller clock (including timezone and DST settings).
What does “Generac weekly test failed” mean?
The controller detected a condition that stopped the exercise. This could be battery/charger issues, oil warning, fuel supply problem, or a sensor alarm. Check for error codes and address the specific issue indicated.
Can a weak battery stop the Generac weekly exercise?
Yes, it’s one of the most common causes. If your battery is older than 3-4 years, proactive replacement often resolves recurring weekly test failures.
How do I manually run a Generac weekly test?
Press OFF, wait 30 seconds, press MANUAL to run a short test (typically 5 minutes), then return to AUTO. If it won’t run, check for error codes, battery condition, and oil level.
What battery does a Generac Guardian need?
Most air-cooled Guardian units use a 12V Group 26R battery. Always confirm whether you need 26R or 26, as terminal orientation differs. Check Generac’s official battery compatibility chart for your specific model.
What oil should I use in my Generac generator?
Most Guardian models specify 5W-30 synthetic oil for a wide temperature range. Always confirm the correct viscosity and change intervals in your owner’s manual.
How often should Generac generators run their weekly test?
The default is once per week, typically for 5-20 minutes depending on your settings. This keeps the engine lubricated, charges the battery, and verifies the system is ready for an actual outage.
What does error code 1100 mean on Generac?
Code 1100 is “Overcrank,” meaning the engine failed to start after multiple attempts. This is often caused by a weak battery, but can also indicate fuel supply issues. Check battery first, then verify fuel is on.
What should I check first if my Generac weekly test isn’t running?
Confirm AUTO mode, check the controller for any message or error code, and verify the exercise schedule and controller clock (including timezone and DST settings).
What does “Generac weekly test failed” mean?
The controller detected a condition that stopped the exercise. This could be battery/charger issues, oil warning, fuel supply problem, or a sensor alarm. Check for error codes and address the specific issue indicated.
Can a weak battery stop the Generac weekly exercise?
Yes, it’s one of the most common causes. If your battery is older than 3-4 years, proactive replacement often resolves recurring weekly test failures.
How do I manually run a Generac weekly test?
Press OFF, wait 30 seconds, press MANUAL to run a short test (typically 5 minutes), then return to AUTO. If it won’t run, check for error codes, battery condition, and oil level.
What battery does a Generac Guardian need?
Most air-cooled Guardian units use a 12V Group 26R battery. Always confirm whether you need 26R or 26, as terminal orientation differs. Check Generac’s official battery compatibility chart for your specific model.
What oil should I use in my Generac generator?
Most Guardian models specify 5W-30 synthetic oil for a wide temperature range. Always confirm the correct viscosity and change intervals in your owner’s manual.
How often should Generac generators run their weekly test?
The default is once per week, typically for 5-20 minutes depending on your settings. This keeps the engine lubricated, charges the battery, and verifies the system is ready for an actual outage.
What does error code 1100 mean on Generac?
Code 1100 is “Overcrank,” meaning the engine failed to start after multiple attempts. This is often caused by a weak battery, but can also indicate fuel supply issues. Check battery first, then verify fuel is on.
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I had a new Generac Generator installed in October. It is now early December. During our first heavy snow fall in Nov., it failed to run after shutting down after 1 minute run time during the weekly test cycle. The red light came on immediately. A technician came out and said that it appeared to be some kind of air lock after testing. He then restarted the unit and the green light came back on. It is now early December and the unit again started to run during the weekly test cycle and shut down after 1 minute and the red light is now back on.
I have a 95 yr. old mother-in-law living with us and need the generator to run if a power outage happens. I went with Generac, even though it cost more than other brands, because of what I understood to be the best service and product on the market.
Not at all happy with the response from HPS.
I’m sorry you’re having trouble with your Generac generator, especially with how important it is for your mother-in-law’s safety. It’s frustrating to have issues with a product you trusted.
It sounds like the problem might be more than just an air lock since it happened again. I’d recommend contacting Generac directly to explain the situation and stress the need for a reliable unit.
Also, you might want to ask HPS for a more detailed inspection or consider getting a second opinion from another technician.
I hope this gets resolved quickly for you.