Generator Group 26 battery
Confirm group size, terminal orientation, and cranking voltage before replacing.
$80-$150
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Error Codes: 1100, 1200, 1300, 2000, 5400
What they mean: Your Generac standby generator is getting battery power and attempting to crank, but it never fires up. The Evolution controller logs specific error codes depending on what it detects during the failed start attempt.
Code 1200 (overcrank) is the most common. The controller gives the engine three cranking cycles, each about 15 seconds with a 15-second pause in between. If the engine hasn’t started after the third attempt, the controller locks out with code 1200.
Code 1100 points to a different problem. The RPM sensor (magnetic pickup) is not sending a speed signal to the controller, so the controller can’t confirm the engine is turning. The engine may be running fine, but the controller thinks it failed to start.
Code 1300 (low oil pressure) and code 2000 (low battery) can prevent starting before the engine even tries to crank. Code 5400 points to a fuel solenoid circuit fault.
Common Causes
- Weak or dead battery — The battery needs 12.4V or more at rest and must stay above 10V while cranking. A battery that passes the rest voltage test but drops below 10V under load is weak and will eventually fail to start.
- Fuel supply problem — Natural gas pressure below 5 inches WC or LP gas pressure below 8 inches WC. Also check for closed fuel valves, air in LP lines after a tank refill, or a tripped gas regulator.
- Fuel solenoid failure — The solenoid that opens the fuel line when the controller signals a start may be stuck closed or electrically failed.
- No spark — Failed ignition module, broken wire to the spark plug, or a kill switch that stays grounded.
- Oil pressure switch open — On some Generac models, the controller reads the oil pressure switch before allowing the engine to fire. If the switch is faulty or the engine has no oil pressure, the controller may crank but never fire the ignition.
- Throttle actuator / stepper motor stuck — The stepper motor may be stuck in the closed position, starving the engine of air.
Step-by-Step Fix
1. Read the error code from the Evolution controller.
Press the OFF button, then press ENTER twice. The controller displays the stored alarm code. Write it down. If no code shows, try pressing the MENU button and scrolling to the Alarm History page.
2. Test the battery at rest and under load.
Measure battery voltage with a multimeter at the battery terminals. A resting voltage below 12.4V means the battery is not fully charged. Below 12.0V means it needs replacement or a full charge from the onboard charger.
Next, measure voltage while cranking. Have someone press the MANUAL START button while you hold the meter leads on the battery terminals. If voltage drops below 10V during cranking, the battery is weak. Replace it.
Check the battery cables for corrosion, especially at the ground connection to the frame. A corroded ground can cause a voltage drop that looks like a bad battery.
3. Check the fuel supply.
Open the main fuel valve fully. On natural gas systems, verify the pressure at the generator inlet. You need a manometer for this measurement. Attach it to the test port on the gas regulator. Target pressure is 5-7 inches WC for natural gas. For LP, target is 8-12 inches WC.
If the generator runs on LP and the tank was recently refilled, air may have entered the lines. Purge the line by cracking the connection at the generator inlet for a few seconds. Tighten it back and retry.
4. Test the fuel solenoid.
Locate the fuel solenoid on the fuel line near the carburetor or mixer. With the generator in MANUAL start mode, you should hear an audible click when the controller energizes the solenoid. No click means the solenoid may be faulty.
Test the solenoid resistance with a multimeter. Unplug the solenoid connector, set the meter to ohms, and measure across the two pins. You should see 20-40 ohms. An open circuit (infinite resistance) or short (near 0 ohms) means the solenoid needs replacement.
5. Check for spark.
Remove the spark plug wire and fit a spare spark plug. Ground the plug threads against the engine block. Crank the engine and watch for a bright blue spark at the plug gap. No spark points to the ignition module, magneto, or kill wire.
Trace the kill wires from the ignition module to the controller. The controller grounds these wires to stop the engine. If the wires are shorted to ground, the engine will never fire. Disconnect the kill wires at the controller and test for spark again. If spark returns, the controller is grounding the kill circuit.
6. Inspect the oil pressure switch.
The oil pressure switch is normally open. It closes when oil pressure rises above 5-8 PSI during cranking. If the switch is stuck open or the wiring is faulty, the controller may crank the engine but never fire the ignition.
Test the switch continuity with a multimeter. With the engine off, the switch should read open (infinite resistance). Disconnect the switch wire at the controller and check for continuity to ground during cranking. No continuity means the switch is not closing.
7. Check the stepper motor / throttle actuator.
The stepper motor controls the throttle plate position. During startup, the controller opens the throttle to a specific position. If the motor is stuck or the linkage is binding, the engine may not get enough air to start.
With the generator off, move the throttle linkage by hand. It should move freely through its full range. Feel for binding or sticking points. Test stepper motor winding resistance. Measure between each pair of the four or six pins. You should see consistent resistance in the 50-100 ohm range across all windings. A shorted or open winding means the stepper motor needs replacement.
Error Code Reference Table
| Code | Meaning | Likely Cause |
|---|---|---|
| 1100 | RPM sensor fault | Magnetic pickup gap wrong, damaged pickup, or broken wire |
| 1200 | Overcrank (engine failed to start) | Fuel supply, spark, or battery weak |
| 1300 | Low oil pressure shutdown | Low oil level, bad oil pressure switch, or wiring fault |
| 2000 | Low battery voltage | Dead or weak battery, failed charger, or parasitic draw |
| 5400 | Fuel solenoid circuit fault | Open or shorted fuel solenoid, or wiring damage |
Parts That May Need Replacement
| Part | Typical Cost | Notes |
|---|---|---|
| Battery (Group 26 or Group 34) | $80-$150 | AGM recommended for standby use |
| Fuel solenoid | $40-$100 | Test resistance first (20-40 ohms) |
| Spark plug | $8-$15 | Gap to 0.030 inches on most models |
| Stepper motor / throttle actuator | $60-$150 | Test winding resistance before ordering |
| Oil pressure switch | $20-$40 | Commonly fails on older units |
| Magnetic pickup (RPM sensor) | $25-$50 | Gap should be 0.040-0.060 inches |
When to Call a Professional
If you have confirmed battery voltage is good, fuel pressure is within spec, and you have spark at the plug but the generator still will not start, stop testing and call a Generac service technician. The problem may be in the Evolution controller itself, a wiring harness fault, or an internal engine problem like low compression.
Do not repeatedly attempt to start a generator that refuses to fire. Each failed attempt drains the battery and can flood the engine with raw fuel, creating a fire hazard. If the generator starts but runs rough, surges, or dies under load, stop running it and call a tech.
Tell the technician: “Generator cranks but will not start. Error code shows [your code]. I checked battery, fuel, and spark. Battery is at [voltage], fuel pressure reads [pressure], and I have [spark/no spark] at the plug.”