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.

• STARTING BATTERIES RUN DOWN (Marginal batteries, connections, or charging system or parasitic loads)
  Fix: 1. Clean and tighten the positive (+) and negative (–) genset battery cable connections. 2. Recharge or replace the battery. Refer to the battery manufacturer's recommendations. 3. Have a battery charging system installed or serviced.
• STarter ENGAGES–DISENGAGES (Cranking voltage dips below 6 volts—low battery charge, poor connections, long cables)
  Fix: 1. Clean and tighten the positive (+) and negative (-) genset battery cable connections. 2. Recharge or replace the battery. Refer to the battery manufacturer's recommendations.
• SERVICE CHECK FAULT—CODE NO. 3 3
  Fix: 1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Open any closed fuel valves and check for an adequate fuel supply. 3. Check for fouled spark plugs. 4. Check air cleaner. 5. Clean and tighten the positive (+) and negative (-) genset battery cable connections. 6. If the condition still exists, contact Cummins/Onan Service.
• OVERCRANK FAULT—CODE NO. 4 4
  Fix: 1. Check fuel level. 2. Open any closed fuel valves. 3. Secure the spark plug lead on the spark plug. 4. Check the spark plugs. 5. Service the air cleaner.
• NO POWER—GENSET RUNNING, RUN LIGHT ON (Line circuit breaker OFF or tripped or faulty wiring)
  Fix: 1. Turn on or reset the line circuit breaker on the genset. 2. Turn on or reset the line circuit breakers on the main distribution panel 3. If the condition still exists, contact Cummins/Onan service.
• LOW OIL PRESSURE FAULT—CODE NO. 2 2
  Cause: The controller sensed that the low oil pressure cutoff did not open within 10 seconds of starting
  Fix: 1. Check engine oil level and add oil as necessary. Repair oil leaks. 2. Drain excess oil. (Excess oil leads to foaming and a consequent loss of oil pressure.) 3. If the oil level is OK, contact Cummins/Onan Service.
• Fuel or exhaust leak
  Fix: Stop the genset immediately and have it repaired before continuing operation.
• Engine does not start after 20 seconds of cranking
  Fix: See Troubleshooting in Section 11 if the engine does not start.
• Engine does not start
  Fix: See Troubleshooting in Section 4
• Electrolyte is a dilute sulfuric acid that is harmful to the skin and eyes. It is electrically conductive and corrosive.
  Fix: (1) Wear full eye protection and protective clothing, (2) Where electrolyte contacts the skin, wash it off immediately with water and seek medical attention, (3) Where electrolyte contacts the eyes, flush thoroughly and immediately with water and seek medical attention, (4) Spilled electrolyte is to be washed down with an acid neutralizing agent. A common practice is to use a solution of one pound (500 grams) bicarbonate of soda to one gallon
• Code No. 4: blink-blink-blink-blink Code No. 4

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.