Generac Code 1100: Overcrank and How to Clear It
Code 1100 means the engine cranked but never started. The controller tries five cranking cycles; if the engine doesn't catch, it locks out with a red light, OVERCRANK on the screen, and code 1100. Generac's own checklist is short: fuel valve open, correct fuel selected, enough propane in the tank, air filter clear, battery good. Clear the alarm, start it in MANUAL, and if it still won't run — or runs rough — that's a dealer call.
| Code | 1100 (OVERCRANK) |
|---|---|
| Applies to | Guardian air-cooled standby (Evolution / Evolution 2.0 / Sync controllers) and Next Generation (Power Zone 200); Nexus units show the word OVERCRANK without a number |
| Severity | Unit will not run |
| DIY | Check, then call — owner-level checks first, then a dealer |
| Last checked |
How to clear Generac code 1100
Before you clear 1100, confirm the fuel shutoff valve is ON: that is the first line of the owner's manual's OVERCRANK entry. Then clear the alarm and start the unit in MANUAL with no load. If it will not start, or starts and runs rough, the manual's answer is a dealer. Each controller's key presses, Nexus and PowerPact included, are on how to clear an alarm.
The OVERCRANK entry reads the same in the Guardian and Next Generation manuals: "Verify fuel line shutoff valve is ON. Clear alarm. Start unit in MANUAL. If it does not start, or starts and runs rough, contact an IASD." (A0001846499 Rev. C, p. 34; A0004332577 Rev. C, p. 37). On a PowerPact, the alarm has its own LED, and the manual's description for it is "Overcranking condition exists" (10000021790 Rev. C, p. 14).
If the overcrank keeps coming back during the weekly exercise, Generac's 1100 article splits the next call by the unit's age: "For generators installed within the last year, contact the installer. For generators older than one year, contact a Generac IASD." After an extended outage it asks propane owners to "Ensure levels are above 35%" before restarting.
What code 1100 means
On an Evolution or Evolution 2.0 controller the display shows the number 1100 and the word OVERCRANK, and the red ALARM LED is on. Generac's error-code list groups 1100 and 1101 together as "Overcrank," a red alarm, with the Mobile Link message "The generator has experienced an overcrank alarm. Please contact a dealer."
Generac's support article defines the condition in one sentence: "Unit turns over but will not start. The engine will attempt to crank 5 times." The owner's manual spells out what those five cycles look like:
- 10 kW units: 15 seconds cranking, 7 seconds rest, then four more cycles of 7 seconds cranking / 7 seconds rest.
- 14–26 kW units: 16 seconds cranking, 7 rest, 16 cranking, 7 rest, then three more cycles of 7 on / 7 off.
If the engine hasn't fired by the end of the fifth cycle, the controller stops cranking and posts the alarm. It will not try again on its own — which is the whole reason you're looking at a dark house.
| Code | Display | Meaning (Generac wording) | Severity | DIY? |
|---|---|---|---|---|
| 1100 | OVERCRANK | Engine cranks but will not start after 5 crank attempts | Unit will not run | Check, then call |
| 1101 | OVERCRANK | Published by Generac in one entry with 1100 — "Overcrank, Error Codes 1100-1101" — with one Mobile Link message and one set of owner checks; no separate owner-facing meaning | Unit will not run | Check, then call |
| — | OVERCRANK (Nexus) | Older Nexus controllers show the word with no number; same protective function | Unit will not run | Check, then call |
A note on 1102: it circulates on forums, but Generac's published error-code list groups Overcrank as 1100-1101 and gives no entry for 1102. Treat anything you read about "1102" as unverified.
Working through Generac's overcrank checks
Everything below is what Generac lists in its 1100 support article and the owner's manual troubleshooting table, in the order most likely to be the problem. Nothing here requires opening the engine.
- Is the fuel shutoff valve on? There's a valve on the gas or propane line at the generator (and usually another at the meter or tank). A valve handle in line with the pipe is open; across the pipe is closed. Contractors, a recent gas-company visit, or a curious kid close these more often than you'd think.
- If it was closed → open it, clear the alarm, start in MANUAL. Expect one or two extra cranks while the line refills.
- If it was open → step 2.
- Propane tank above 30 %? Generac wants LP above 30 %. Below that, tank pressure on a cold day can't feed the regulator at full engine demand. Natural gas customers: skip to step 3, but ask yourself whether the utility had an outage or pressure drop.
- If the tank is low → fill it, then retest. Ask the supplier to check regulator delivery pressure while they're there.
- Is the fuel selection right? Air-cooled Guardians are convertible between natural gas and propane; the fuel jet and (on some units) a controller setting must match. A unit installed on NG but flipped to LP during a service visit will crank forever. The installing dealer records the fuel setting; check with them rather than changing anything yourself.
- If wrong → contact the installing dealer; changing fuel involves the gas train.
- Air filter blocked or iced? Open the air box and look. A filter packed with cottonwood fluff, mud-dauber nests, or ice after a storm will starve the engine on the crank. Replace, don't wash (paper element).
- Part numbers: 0J8478S (14–26 kW), 0E9371AS (10 kW) on current Evolution 2.0 units; older units use 0J8478 / 0E9371A — confirm against your owner's manual.
- Battery. A battery that will spin the starter for one 16-second cycle but sags by the third is a classic overcrank. From the MAIN MENU, go to BATTERY: GOOD means move on; CHECK BATTERY means replace it. Generac specifies a Group 26R wet cell, 540 CCA minimum (or Group 35 AGM, 650 CCA). Also check that the charger's AC feed hasn't been tripped — a 2770 or 2780 warning in the alarm log points that way.
- If the battery is weak → replace it (Generac part 0H3421S is the Group 26R). Clear the alarm and retest.
- For group size, published part numbers, and replacement checks, use the Generac battery replacement guide.
- Clearance and snow. Generac asks for three feet of clearance all around and no snow over the intake louvers. Buried units crank rich and won't light.
- Still overcranking? Clear the alarm once more and try MANUAL while you stand next to the unit. What you hear is worth writing down before you call: cranking with no cough at all is a different starting point for the technician than a cough that never catches. Either way the owner's part ends here. Fuel pressure at the regulator, the mixer and valve clearance are all measured rather than inspected, and Generac's instruction for an overcrank that survives the checks above is an Independent Authorized Service Dealer.
Filters, plugs and battery for an overcrank
Only parts Generac lists in its own owner's manuals for the 10–26 kW air-cooled line are shown. Older 8–20 kW Nexus units use different filters — check your manual's "Specifications" table.
| Part | Part number | Fits | Where verified |
|---|---|---|---|
| Battery, Group 26R, 540 CCA | 0H3421S | 10–26 kW air-cooled Guardian | Owner's manual A0001846499 / A0000973303 |
| Air filter | 0J8478S (older: 0J8478) | 14–26 kW | Owner's manuals |
| Air filter | 0E9371AS (older: 0E9371A) | 10 kW | Owner's manuals |
| Spark plug (RC12YC equivalent) | 0G0767A | 14–26 kW (two plugs) | Owner's manuals |
| Spark plug | 0G0767B | 10 kW (one plug) | Owner's manuals |
| Oil filter | 070185ES (older: 070185E) | 10–26 kW | Owner's manuals |
| Control panel fuse | 0D7178T | 10–24 kW | Owner's manual A0000973303 |
Generac sells these bundled as maintenance kits keyed to your generator's model number (G00xxxxx), not its kW rating. The kit article on Generac's support site lists the current kit numbers.
When an overcrank needs a dealer
- The unit cranks fine, fuel is confirmed on and at pressure, the filter is new, the battery reads GOOD, and it still won't catch.
- It starts in MANUAL but overcranks again the next time it tries on its own (points to fuel pressure under load or a marginal battery/charger).
- You smell gas at the unit, or the fuel selection looks wrong — the gas train is licensed work.
- The alarm log shows 1100 alongside 1505 (RPM sense loss) or 2770/2780 (charger) — a technician needs the whole history.
- Generac's support line is 1-888-436-3722; the dealer locator is on generac.com. Warranty work must go through an Independent Authorized Service Dealer (IASD).
Codes that follow a failed start
Generac names a weak battery among the causes of both 1100 and the RPM sense family: its overcrank article lists "Low battery", and its RPM article lists "Weak or bad battery". So an overcrank followed by 1505 RPM Sense Loss on the next try sends you to the battery first, as the 1505 page explains. An engine that starts and then shuts down is a different alarm: 1501 if the display shows RPM SENSE LOSS, 1300 if it shows LOW OIL PRESSURE. What every light on the unit means is on Generac lights and alarms.
Not sure the generator can carry the load?Generator Wattage Calculator Running watts, the largest starting surge, and a generator class from manufacturer charts.Frequently asked questions
Can I just clear the 1100 alarm and try again?
Yes — clearing the alarm and starting in MANUAL is part of Generac's own procedure, and an overcrank caused by a closed valve or a cold tank will start once the cause is gone. What the procedure does not allow is repeated clearing in place of a fix. If it starts, use the checks above to find out why it didn't the first time, before the next outage asks the same question.
Why did my generator overcrank during its weekly exercise but start fine in MANUAL?
The exercise cycle happens at a set time regardless of weather; a cold propane tank, a marginal battery, or ice in the air intake can fail then and be fine an hour later. Check the battery reading and the propane level first.
Does code 1100 mean the starter is bad?
Not by itself. 1100 says the engine turned over and didn't fire. If the starter were dead the unit would not crank at all, and an alarm from the RPM SENSE LOSS family is the more likely display; Generac publishes 1500–1522 as one family with the same owner troubleshooting for every number in it. A starter that spins slowly on a good battery is a dealer diagnosis.
What is the difference between 1100 and 1101?
Both display OVERCRANK, and Generac publishes them as a single entry — "Overcrank, Error Codes 1100-1101" — with one Mobile Link message and one set of owner checks. No separate meaning for 1101 appears in its owner-facing documents, so treat the two numbers as the same fault.
Will Mobile Link tell me it's an overcrank?
Yes. Generac's code list gives the Mobile Link message as "The generator has experienced an overcrank alarm. Please contact a dealer," and the app's status history shows the code number if the unit is enrolled.
Parts and consumables
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If a part number above matches your manual, these searches will find it. Verify the fit against your model number before ordering.
- Generac 0H3421S Group 26R battery (10–26 kW air-cooled)Find on Amazon
- Generac air filter 0J8478S (14–26 kW) or 0E9371AS (10 kW)Find on Amazon