Generac Generator Code 1505: Low Oil Pressure Shutdown

Quick Answer

Generac 1505 low oil pressure is a critical shutdown that requires immediate attention. Unlike many Generac codes that are sensor or starting issues, 1505 means the engine was running and lost oil pressure - which causes bearing damage within seconds if not stopped. Generac standby generators have a dedicated low-oil pressure shutdown solenoid that is separate from the oil pressure sensor.

Code 1505 almost always shows up around hour 48-72 of a continuous run during a multi-day outage when nobody went out to check the oil. Air-cooled engines like these burn oil by design, and with only 1.9 quarts in the crankcase, losing even half a quart matters. If the oil level's fine, I'm looking at the pressure switch wire where it runs past the engine tin. Vibration rubs those wires raw and grounds them out right when you need power most.

GeneracGeneratorSeverity: criticalDifficulty: intermediate75% DIY Success

Time to Fix

20–120 min

Difficulty

intermediate

Parts Cost

$8 – $45

Tools Needed

Phillips #2 screwdriver, Flathead screwdriver

What Does the 1505 Code Mean?

Here's the deal with 1505: it sounds way scarier than it usually is. Most of the time it's a maintenance thing or a bad $30 sensor, not a blown engine. Generac uses a normally-closed oil pressure switch, so if that switch cracks or the wire falls off and grounds out, the controller thinks you've lost pressure and shuts everything down. It's a $30 fix that can save a $5,000 engine if you catch it right.

Most Likely Causes

Based on aggregated repair data, here is the probability breakdown for this error code:

Oil level low (missed service interval)40%

Oil pressure sender failed (false reading)24%

Low-oil shutdown solenoid failed14%

Oil viscosity wrong for temperature12%

Oil pump failure10%

Symptoms You May Notice

Display shows 1505 and the engine is completely dead, won't crank at all.
Engine was running totally fine during the outage and then just stopped mid-run with zero warning.
There's a faint click from the solenoid right before the engine cuts out if you're standing close enough to hear it.
Oil warning LED is lit up solid red on the control panel.
You might have heard a brief deep knock or rattle right before the shutdown, which is a very bad sign and means get a pro on the phone.

Can you reset a Generac generator to clear the 1505 code?

Flip the breaker to the OFF position first so the generator does not try to take a load immediately. Press the OFF button on the control panel, then press ENTER to clear the 1505 alarm. Once the screen is clear, check your oil level one last time. Only then should you press MANUAL to test the unit before putting it back into AUTO mode.

Tools Required for Diagnosis

Phillips #2 screwdriverFlathead screwdriver3/8" drive socket setOil filter wrenchMultimeter with continuity modeFunnel for adding oilShop rags or paper towelsElectrical tape and heat shrink tubing

Diagnostic Checklist

Follow these steps in order. We start with the easiest external fixes before opening up the machine.

ComponentComponent Under Test

Expected Range0–5 ohms

ConditionIf Open (OL) or infinite, replace component.

Replacement Parts

If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.

Part Name	OEM Number	Estimated Price
Generac Low Oil Pressure Shutdown Solenoid0C3029 · $25–$45	0C3029	$25 – $45
Generac Oil Pressure Sender0G8442 · $20–$40	0G8442	$20 – $40
Synthetic Motor Oil 5W-30N/A · $8–$12	N/A	$8 – $12

Frequently Asked Questions

Can 1505 be a false alarm?

Yeah, pretty often actually. These generators live outside in all kinds of weather and the oil pressure switch takes a beating from heat and vibration year after year. The switch itself can crack or fail internally and send a false low-pressure signal even when oil pressure is totally fine. Also if you're running 10W-30 conventional instead of 5W-30 full synthetic in cold temps, the oil can be thick enough on startup that pressure takes a couple extra seconds to build, and the controller trips before it gets there. Switching to full synthetic basically eliminates that cold-start false trip for good.

My Generac threw 1505 during a storm. Did I lose power protection?

Unfortunately yeah, 1505 is a hard lockout. The unit stays dead until a human clears it manually, so if it tripped during the outage and nobody caught it, you were running on nothing. Go check the oil level first. If it's low, fill it and reset it. If it's full, you can try resetting once and running it in manual for ten minutes to see if it holds. If it trips again right away, leave it off. Running it with a real oil pump failure will cost you a complete engine replacement, and that's a $2,000-$4,000 bill depending on the model.

How often should I check the oil during an extended outage?

Every 24 hours minimum if it's been running continuously. I know that sounds like a lot but these air-cooled engines only hold 1.9 quarts and they do burn some oil by design. During a long outage I've gone back to check a unit after 30 hours and found it half a quart low already. Half a quart in a 1.9 quart system is a big deal. Keep a couple quarts of 5W-30 full synthetic and a spare oil filter on your shelf right now, before you need them. You don't want to be driving around a dark neighborhood looking for supplies at 2am in a storm.

What does it cost to fix a Generac 1505?

Depends completely on what caused it. Just low oil? Under $15 in synthetic. Oil pressure sender failed? The part's $25-$40 and takes about 20 minutes to swap out. Chafed wire? Basically free if you've got electrical tape and heat shrink. Now if the oil pump actually failed or there's bearing damage from running dry, you're looking at $800-$2,500 or more in parts and labor depending on how bad it got. The sooner you catch it the cheaper the fix. That's basically the whole point of that 1505 shutdown code.

Can I just reset it and see what happens?

Only after you've physically checked the oil level on the dipstick. Don't skip that step. If the oil is low and you reset and let it run, you could destroy the engine in minutes. But if you've confirmed the oil is full and you suspect a sensor or wire issue, one reset attempt is totally reasonable. Stay with the unit for at least 10 minutes after the reset and watch for the code to come back. If it trips again immediately, something is actually wrong and you need to dig deeper before running it again.

Related Generac Generator Error Codes

Code: HUBGenerac Generator Error Codes: Complete Reference Code: 2800Generac 2800: Overcrank Code: 1100Generac 1100: RPM Sense Loss

Models Known to Experience 1505 Errors

This repair applies to most Generac generators with this error code. Common model numbers include:

Guardian 22kW 7043, Guardian 24kW 7210, Guardian 20kW 7039, Guardian 16kW 7035, Guardian 26kW 7291, EcoGen 15kW 6438, Protector 20kW QS020, Protector 25kW RG025

Written by

Sarah Kim

Smart Home & Specialty Appliance Tech · 12 years experience

Last verified for technical accuracy on March 15, 2026