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ErrBase

Generac Generator Code 1501: Oil Pressure Sensor Fault

Quick Answer

Generac 1501 is a fault code on Generac standby generators. Code 1501 specifically indicates the oil pressure sensor circuit has a fault - either open circuit, short circuit, or reading out of expected range. Unlike 1505 which indicates actual low oil pressure, 1501 is a sensor circuit problem.

Generac 1501 is a fault code on Generac standby generators. Code 1501 specifically indicates the oil pressure sensor circuit has a fault - either open circuit, short circuit, or reading out of expected range. Unlike 1505 which indicates actual low oil pressure, 1501 is a sensor circuit problem. The Generac Evolution controller stores fault history accessible by pressing OFF then ENTER twice. This code should be addressed promptly to ensure the generator is ready for the next power outage.

GeneracGeneratorSeverity: mediumDifficulty: intermediate75% DIY Success
Time to Fix
30–180 min
Difficulty
intermediate
Parts Cost
—
Tools Needed
Multimeter, Socket wrench set

What Does the 1501 Code Mean?

Code 1501 specifically indicates the oil pressure sensor circuit has a fault - either open circuit, short circuit, or reading out of expected range. Unlike 1505 which indicates actual low oil pressure, 1501 is a sensor circuit problem.

Most Likely Causes

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

Oil pressure sensor wiring open circuit40%
Sensor connector corroded24%
Oil pressure sensor failed14%
Wiring chafed against engine components12%
Controller input circuit damaged10%

Symptoms You May Notice

  • Code 1501 on controller display
  • Generator alarm light active
  • Generator may have shut down
  • Audible alarm from controller

Can you reset a Generac generator to clear the 1501 code?

Press ALARM RESET on the controller. Switch to AUTO for standby mode. Test with MANUAL RUN to verify fix.

Tools Required for Diagnosis

MultimeterSocket wrench setFlashlight

Diagnostic Checklist

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

1

Read and note the 1501 alarm code from the controller display

Read and note the 1501 alarm code from the controller display. Press OFF then ENTER twice to check fault history.

2

Press ALARM RESET to clear the code

3

Based on the specific code, inspect the related component

Frequently Asked Questions

Is Generac code 1501 serious?
Code 1501 indicates oil pressure sensor wiring open circuit. While not always an emergency, it means your generator may not be ready for the next power outage. Address it at your next service visit or sooner if outages are expected.
Can I reset code 1501 myself?
Yes. Press the ALARM RESET button on the controller. If the code returns immediately, the fault is still active. If it clears and stays clear through the next exercise cycle, it was likely a transient condition.
Should I call a Generac dealer for this code?
If the code returns after reset, or if you are not comfortable diagnosing engine and electrical systems, yes. Generac authorized dealers have diagnostic software that provides more detail than the controller display alone.

Related Generac Generator Error Codes

Code: HUBGenerac Generator Error Codes: Complete Reference

Models Known to Experience 1501 Errors

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

Guardian 22kW 7043, Guardian 24kW 7210, Guardian 16kW 7035, EcoGen 15kW, Protector 20kW

Last verified for technical accuracy on March 15, 2026