Generac Error Code 1300: Low Oil Pressure
Code 1300 means the engine shut itself down to protect the crankshaft. The low oil pressure switch opened while the generator was running, the controller killed the engine, and it won't restart until you clear the alarm. Generac's fix is the one you'd guess: let it cool 30 minutes, check the dipstick, add oil if it's low, make sure the fill cap, drain cap, and filter are tight, look for leaks — then OFF → ENTER (twice on some units) → AUTO. If the oil level is correct and 1300 comes back, that's a dealer call: the switch, the wiring, or the engine itself.
What code 1300 means
Generac's code list is terse — "1300: Low Oil Pressure" — and its support article says the code "indicates the low oil pressure sensor has triggered a shutdown due to inadequate oil levels," with the usual reason being oil consumption, a leak, or skipped maintenance.
The diagnostic manual describes it as the default extended alarm for low oil pressure, occurring while running, and sends the technician to "Test 61 – Check Oil Pressure Switch (LOP) and Wire 86." The switch sits on the engine and reports to the controller over Wire 86; when oil pressure falls, the controller stops the engine.
Two details that matter:
- The switch measures pressure, not level. Low level is the usual reason pressure drops (the pump sucks air on a tilt or a cold crank), but a good level with a failed switch, a chafed Wire 86, or a worn oil pump produces the same alarm.
- The threshold isn't in current owner's manuals. The Nexus-era manual gives 5 psi with a five-second delay on startup and seven seconds while running. Current Evolution manuals don't publish a number. If a dealer quotes a figure for your unit, that's theirs, not Generac's public spec.
| Code | Display | Meaning (Generac wording) | Severity | DIY? |
|---|---|---|---|---|
| 1300 | LOW OIL PRESSURE | Default extended alarm for low oil pressure, occurred while running; check oil level and pressure | Unit will not run | DIY-friendly |
| — | LOW OIL PRESSURE (Nexus) | Oil pressure below 5 psi (5 s startup delay, 7 s running delay); text alarm, no number | Unit will not run | DIY-friendly |
Reset procedure (as the manual states it)
From Generac's 1300 support article, in order:
- Let the generator cool for at least 30 minutes. Oil settles; checking hot gives a false low.
- Pull the dipstick, wipe, reinsert fully, read. Oil should sit between the marks; add a little at a time.
- Confirm the oil fill cap, oil drain cap, and oil filter are hand-tight. A filter left a half-turn loose after a service will weep and then lose pressure under load.
- Look under and around the engine for fresh oil.
- Clear the alarm:
- Evolution / Evolution 2.0 / Sync: press OFF, then ENTER (the 1300 article says twice), then AUTO.
- Power Zone 200 (Next Generation series): hold OFF for 3 seconds, then AUTO.
- Nexus: rocker to OFF, ENTER twice, rocker to AUTO.
- Press MANUAL and let it run five minutes. Watch the display and listen.
The owner's manual's whole entry for this alarm: "Check oil level and add oil as needed. If oil level is correct, contact an IASD." That second sentence is the important one.
Step-by-step diagnosis
- Read the dipstick cold. Low → add the correct oil (table below) to the full mark, no higher. Overfilling foams the oil and can trip the same alarm.
- Was it low? → go to step 2 anyway. Oil doesn't leave on its own.
- Full and clean? → step 4.
- Where did the oil go? Air-cooled Generacs run hard and hot; some consumption between 200-hour services is normal, but a quart down in a season isn't. Check the drain hose/cap (many units have a drain hose routed to the front), the filter gasket, the valve cover gaskets, and the crankcase breather. A wet spot under the unit or oil on the enclosure floor tells you.
- Leak found at a cap or filter → tighten, top off, clear, retest.
- Leak at a gasket → dealer.
- When was the last oil change? Schedule A is every two years or 200 hours (first change at 25 hours). Old oil thins, and a plugged filter starves the switch. If it's overdue, do the service now (oil + filter 070185ES), then clear.
- Level is fine and it still trips? Now it's the switch, the wire, or actual pressure. Look at Wire 86 where it leaves the switch — heat, rodents, and vibration break it. You can look; the test is the dealer's (Test 61 in the diagnostic manual, "Check Oil Pressure Switch (LOP) and Wire 86").
- Did it happen at start-up or under load? A trip in the first few seconds of a cold-weather start with correct oil often points to viscosity: an engine still on the factory 5W-20 in a Minnesota January will show low pressure until it warms. Generac's current manual specifies its 5W-20 GEO oil year-round; older manuals specified synthetic 5W-30 for all temperatures and, for Nexus units, SAE 30 above 32 °F. Running the wrong grade for your manual's year is a real cause.
- Tilted unit? A pad that's settled a few degrees puts the pickup above the oil at one end. Check the enclosure with a level; anything obvious → dealer to re-set the pad.
Oil type and capacity (from Generac's manuals)
| Unit | Engine | Oil capacity (with filter) | Oil grade (manual year) | Where verified |
|---|---|---|---|---|
| 10 kW | 460 cc | approx. 1.1 qt (1.03 L) | 5W-20 GEO after 25-hr break-in (2023); synthetic 5W-30 (2020) | Owner's manuals A0001846499 / A0000973303 |
| 14–18 kW | 992 / 999 cc twin | approx. 2.2 qt (2.1 L) | same | Owner's manuals |
| 20–26 kW | 999 cc | approx. 1.9 qt (1.8 L) | same | Owner's manuals; 20–24 kW spec sheet |
| 8 kW (Nexus era) | 410 cc | approx. 1.5 qt | SAE 30 above 32 °F; 10W-30 40 °F to −10 °F; synthetic 5W-30 at 10 °F and below | Nexus 8–20 kW owner's manual |
| 13–20 kW (Nexus era) | 992 / 999 cc | approx. 1.9 qt | same | Nexus 8–20 kW owner's manual |
| Oil filter | 070185ES (older 070185E; Nexus 070185F) | all air-cooled Guardian | Owner's manuals |
Oil must meet API service class SJ, SL, or better. Generac sells its GEO oil and the filter in model-number-keyed maintenance kits; the kit article on its support site lists current numbers.
A low-oil-pressure switch part number isn't shown here because none could be confirmed on a Generac or authorized-dealer page — the numbers on auction sites vary by engine and psi rating, and the wrong one will either nuisance-trip or never trip.
Repair or replace?
1300 is the cheapest alarm in the book when it's oil, and one of the most expensive when it isn't. Oil and a filter: $40–$60 in parts. A switch or Wire 86 repair: an hour of dealer time. Genuine low pressure on a unit with correct oil — worn pump, bearing wear from having been run low — is an engine rebuild or a short block, which on an older 8–17 kW unit can approach the price of a new generator. That's the only scenario where replacement is the honest recommendation, and it's usually a unit that ran dry during a long outage.
When to call a dealer
- Oil level and grade are correct and 1300 returns.
- You found oil at a gasket, the breather, or inside the enclosure rather than at a cap or filter.
- The engine ran for any length of time with the dipstick below the low mark — ask for a pressure test before the next outage.
- The unit knocks, smokes, or sounds different after the reset.
- Generac support: 1-888-436-3722. Warranty work goes through an Independent Authorized Service Dealer.
Parts and supplies mentioned on this page
Use the grade your manual's year specifies; the 2023 manual moved to Generac's 5W-20 GEO oil after break-in.
- Generac 5W-20 gaseous engine oil (GEO), 2-quartCheck price on Amazon
- Generac oil filter 070185ESCheck price on Amazon
- Generac air-cooled maintenance kit (oil, filters, plugs)Check price on Amazon
Related codes and symptoms
A unit that starts, runs a few seconds, and shuts down with no oil alarm is more likely showing 1505 RPM Sense Loss. If 1300 shows up alongside a 1400 High Temperature, stop and call — the two together suggest the engine ran hot and low.
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 add regular car oil to my Generac to clear a 1300?
In a pinch, a synthetic oil of the grade your manual specifies (synthetic 5W-30 per the 2020 manual; SAE 30 or 10W-30 by temperature for Nexus units) meeting API SJ/SL or better will get you through an outage. Generac's current manual specifies its own 5W-20 GEO oil after break-in, and using it keeps warranty questions simple.
How often should the oil be changed on a Generac standby?
Per the owner's manual: first change at 25 hours, then every two years or 200 hours of running, whichever comes first. Air filter, spark plugs, and valve clearance are every four years or 400 hours.
Does the low oil pressure switch shut the unit down instantly?
Nexus-era manuals give a five-second delay at startup and seven seconds while running, so a momentary dip on a hard motor start doesn't trip it. Evolution manuals don't publish the timing.
My oil is full but the alarm keeps coming back. Is the sensor bad?
Possibly, but it can also be the wire to the sensor (Wire 86), a filter that's collapsing, or real low pressure. Generac's instruction for correct oil plus a repeat alarm is to contact a dealer; the test involves a mechanical gauge on a running engine.
Will the generator restart on its own after a 1300?
No. Alarms latch. You (or the dealer) must clear it at the panel before it will respond to an outage.