Commercial Lawn / Turf Engine Fault Codes
Zero-turn mowers, walk-behinds, and stand-on mowers from Toro, Exmark, Scag, Bad Boy, Wright, Ferris, and Hustler all run on a small set of engines: Kohler Command, Kawasaki FX/FR/FS, or Briggs Vanguard. Most are air-cooled commercial gas V-twins from 18-40 HP. EFI variants on the higher-HP models use OBD-style P-codes; carbureted units rely on simple blink-fault LEDs and visual diagnostics. This hub covers the codes you actually see in landscape fleets and at the OPE service shop.
48 fault codes documented· Kohler / Kawasaki / Briggs · Commercial mower fleets
Most Common Mower Engine Fault Codes
Showing 30 of 48 Lawn / Turf codes across Kohler Command, Kawasaki FX, and Briggs Vanguard, sorted by severity.
KAWASAKI-FX-BLINK-2 critical
Low Oil Pressure Shutdown on Carbureted Engine
KAWASAKI-FX-BLINK-3 critical
Engine Overheat Shutdown High Cylinder Head Temp
KOHLER-COMMAND-BLINK-2 critical
Low Oil Pressure Shutdown Detected
KOHLER-COMMAND-BLINK-3 critical
Cylinder Head Overheat Shutdown Detected
BRIGGS-VANGUARD-P0122 serious
Throttle Position Sensor Voltage Below Normal Range
BRIGGS-VANGUARD-P0123 serious
Throttle Position Sensor Voltage Too High
BRIGGS-VANGUARD-P0201 serious
Cylinder 1 Fuel Injector Circuit Fault
BRIGGS-VANGUARD-P0202 serious
Cylinder 2 Injector Circuit Open or Shorted
BRIGGS-VANGUARD-P0301 serious
Cylinder 1 Misfire Detected on V-Twin
BRIGGS-VANGUARD-P0302 serious
Cylinder 2 Misfire Detected on EFI Engine
BRIGGS-VANGUARD-P0335 serious
Crankshaft Position Sensor Signal Lost or Missing
BRIGGS-VANGUARD-P1626 serious
Theft Deterrent Fuel Enable Signal Lost
KAWASAKI-FX-P0122 serious
Throttle Position Sensor Voltage Too Low
KAWASAKI-FX-P0123 serious
Throttle Position Sensor Voltage Too High
KAWASAKI-FX-P0201 serious
Cylinder 1 Injector Circuit Open or Shorted
KAWASAKI-FX-P0202 serious
Cylinder 2 Injector Circuit Fault Detected
KAWASAKI-FX-P0301 serious
Cylinder 1 Misfire Detected on EFI Engine
KAWASAKI-FX-P0302 serious
Cylinder 2 Misfire Detected on V-Twin
KAWASAKI-FX-P0335 serious
Crankshaft Position Sensor Signal Lost
KOHLER-COMMAND-P0122 serious
Throttle Position Sensor Voltage Too Low
KOHLER-COMMAND-P0123 serious
Throttle Position Sensor Voltage Too High
KOHLER-COMMAND-P0201 serious
Cylinder 1 Injector Circuit Open or Shorted
KOHLER-COMMAND-P0202 serious
Cylinder 2 Fuel Injector Circuit Fault
KOHLER-COMMAND-P0301 serious
Cylinder 1 Misfire Detected Engine Running Rough
KOHLER-COMMAND-P0302 serious
Cylinder 2 Misfire Detected on EFI Engine
KOHLER-COMMAND-P0335 serious
Crankshaft Position Sensor Signal Lost or Missing
BRIGGS-VANGUARD-P0107 moderate
MAP Sensor Signal Voltage Below Normal Range
BRIGGS-VANGUARD-P0108 moderate
MAP Sensor Signal Voltage Above Normal Range
BRIGGS-VANGUARD-P0112 moderate
Intake Air Temperature Sensor Signal Too Low
BRIGGS-VANGUARD-P0117 moderate
Engine Coolant Temperature Sensor Signal Too Low
Mower Engine Brands
| Brand | Applications | Notes |
|---|---|---|
| Kohler Command / Command Pro | CV640, CV730, ECV730 EFI, ECV749 EFI, ECV880 EFI -- 19-37HP V-twin gas | Air-cooled commercial gas. Found on Toro, Exmark, Scag, Bad Boy, Wright, Ferris, Hustler. EFI variants use OBD-II style P-codes; carbureted CV-series use blink-style fault LEDs. |
| Kawasaki FX / FR / FS | FX730V, FX801V, FX850V, FX1000V, FR691V, FS730V -- 14-38HP V-twin gas | Dominant alongside Kohler in commercial mowers. Same OEM list as Kohler. Carb and EFI variants. Diagnostic via KDS for EFI; visual/mechanical for carb. |
| Briggs Vanguard | 18HP / 23HP V-Twin Pro, 28HP / 31HP / 37HP / 40HP EFI Big Block | Commercial-grade Briggs (distinct from consumer). EFI Big Block popular on zero-turns above 60-inch decks. |
Common Mower Engine Issues
- Misfire codes (P0301, P0302) on V-twin engines -- ignition coil, spark plug, or injector wear
- Idle speed too low (P0506) -- vacuum leak, dirty throttle body, or stuck IAC valve on EFI
- Throttle position sensor faults (P0122, P0123) -- TPS connector damage from vibration
- Carbureted blink-2 (low oil pressure shutdown) -- low oil after extended mowing
- Carbureted blink-3 (overheat shutdown) -- grass and chaff in cooling fins
- Hard starting after winter storage -- stale fuel, gummed carb, weak battery
- EFI lean codes (P0131, P0420) -- vacuum leaks at intake, vacuum lines, or PCV