Honda GX670 Engine

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Symptoms & remedies

Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.

• Underfrequency fault (controller not able to regulate to rated frequency) 15
  Cause: Genset overloaded
  Fix: Turn the genset line circuit breaker OFF. If the genset runs without shutting down, run the genset with fewer connected loads.
• Overcrank fault (cranking exceeded 20 seconds without engine starting) 4
  Cause: Closed fuel shutoff valves
  Fix: Open any closed fuel shutoff valves.
• Mechanical fault (engine stopped without command by controller) 36
  Cause: LPG fuel tank less than half full; insufficient vaporization; LPG with more than 2.5 percent butane will not vaporize below 32° F (0° C)
  Fix: Fill the LPG fuel tank if less than half full. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization required to keep up with genset fuel demand. Use HD-5 grade LPG.
• No response when the control switch in the Run position (marginal batteries, connections, or charging system)
  Cause: Fuse F1 (B+) blown
  Fix: Replace Fuse F1 (B+) if blown.
• No power—genset running, Run light on (line circuit breaker OFF or tripped or faulty wiring)
  Cause: Line circuit breaker on the genset OFF or tripped
  Fix: Turn on or reset the line circuit breaker on the genset.
• Undervoltage fault (controller not able to regulate to rated voltage) 13
  Cause: Genset overloaded
  Fix: Turn the genset line circuit breaker OFF. If the genset runs without shutting down, run the genset with fewer connected loads.
• Field overload fault (too many low power factor loads) 38
  Cause: Too many appliances running at the same time, especially those with high motor starting loads such as air conditioners
  Fix: Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners.
• Speed sense fault (controller failed to sense quadrature frequency) 45
  Cause: Pin connections or pin condition faulty
  Fix: Check all pin connections and pin condition. Replace as necessary.
• Low oil fault (the controller sensed that the low oil pressure cutoff did not open within 10 seconds of starting or closed during operation) 2
  Cause: Low engine oil level; oil leaks
  Fix: Check engine oil level and add oil as necessary. Repair oil leaks.
• Low cranking speed fault (cranking speed less than 180 rpm for more than 2 seconds) — when engine is cranking slowly 32
  Cause: Loose or dirty battery cable connections
  Fix: Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset.
• Low cranking speed fault (cranking speed less than 180 rpm for more than 2 seconds) — when engine appears to be cranking normally 32
  Cause: Open field windings circuit (pins P1-1 and P1-10); speed sense signal is generated from this circuit
  Fix: Disconnect genset control connector P1 (refer to Section 8 to remove connector P1) and check for electrical continuity across pins P1-1 and P1-10 (field windings). If the circuit is open, service the generator brush block and slip rings and repeat the test. Service or replace the generator rotor if the circuit is still open (Section 7).
• AC output sense fault (controller unable to sense output voltage) 27
  Cause: AC sense circuitry (Voltage Sense Input signal to genset control PCB) open
  Fix: Check AC sense circuitry (Voltage Sense Input signal to genset control PCB) for continuity. See Wiring Diagram in Section 11.
• Overvoltage fault (controller not able to regulate to rated voltage) 12
  Cause: Brushes and slip rings need service
  Fix: Service the brushes and slip rings as necessary (see Servicing Brushes and Slip Rings in Section 8).
• Overfrequency fault (controller not able to regulate to rated frequency) 14
  Cause: Governor linkage binding
  Fix: Check the governor linkage for binding and service as necessary (see Governor Linkage and Actuator in Section 6).
• Generator rotor fault (controller failed to sense field voltage) 41
  Cause: Brushes faulty
  Fix: Check brushes (see Section 7).

Compiled from service & troubleshooting documentation across every generator set that uses the Honda GX670.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.