Northern Lights NL668T2 troubleshooting: 10 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Northern Lights NL668T2 — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Lack of Engine Power | Engine overload, Intake air restriction, Clogged primary fuel filter element, Clogged secondary fuel filter element, Improper type of fuel, Overheated engine, Below normal engine temperature, Improper valve clearance, Dirty or faulty injection nozzles, Injection pump out of time, Turbocharger malfunction | Reduce load, Service air cleaner, Clean or replace filter element, Replace secondary filter element, Consult supplier and use proper type of fuel for operating conditions, See “Engine Overheats” in next category, Remove and check thermostat, Reset valves (Best done by dealer), See your local dealer, Replace injectors (Best done by dealer), See your local dealer |
| Engine Runs Irregularly or Stalls Frequently | Below normal engine temperature, Clogged primary fuel filter element, Clogged secondary fuel filter element, Water or dirt in fuel system, Dirty or faulty injection nozzles, Air in fuel system, Improper type of fuel | Remove and check thermostat, Clean or replace filter element, Replace secondary filter element, Drain, flush, fill, and bleed system, Have your dealer check injection nozzles, Inspect clamps and hoses on suction side. of fuel pump for air leak, Consult fuel supplier and use proper type of fuel for operating conditions |
| Engine Overheats | Engine overloaded, Low coolant level, Cooling system needs flushing, Defective thermostat, Defective temperature gauge/sender | Reduce load, Fill tank or radiator to proper level, Check hoses for loose connections and leaks, Flush cooling system, Remove and check thermostat, Check water temperature with thermometer and replace gauge or sender if necessary |
| Engine Knocks | Insufficient oil, Injection pump out of time, Below normal engine temperature, Engine overheating | Check dipstick, Call your dealer, Call your dealer, Check your thermostat, Check water temperature to see if temperature gauge is working properly, See “Engine Overheating” section |
| High Fuel Consumption | Improper type of fuel, Clogged or dirty air cleaner, Engine overload, Improper valve clearance, Injection nozzles dirty, Injection pump out of time, Engine not at proper temperature, Defective turbocharger | Use correct fuel for temperature, Service air cleaner, Reduce load, See your local dealer, See your local dealer, Check your thermostats, Check water temperature with thermometer and replace gauge if necessary, See you local dealer |
| Low Oil Pressure | Low Oil Level, Improper type of oil, Partially plugged oil filter | Fill crankcase to proper level, Drain and fill crankcase with correct oil, Replace filter |
| High Oil Consumption | Break-in period, Crankcase oil too light, Oil leaks, Restricted crankcase vent tube, Engine overheats, Defective turbocharger | Oil consumption decreases after break-in, Use proper viscosity oil, Check for leaks in lines around gaskets and drain plug, Clean the vent tube, See “Engine Overheats” in previous category, See you local dealer |
| Engine Emits Black or Gray Exhaust Smoke | Clogged or dirty air cleaner, Defective muffler (back pressure too high), Improper fuel, Engine overload, Injection nozzles dirty, Engine out of time, Defective turbocharger | Service air cleaner, Have dealer check back pressure, Use correct fuel for temperature, Reduce load, See your local dealer, See your local dealer, See your local dealer |
| Engine Emits White Exhaust Smoke | Improper fuel, Cold engine, Defective thermostat, Engine out of time, Defective injection nozzles | Use correct fuel for temperature, Warm up engine to normal operating temperature, Remove and check thermostat, See your local dealer, See your local dealer |
| Engine Hard to Start or Will Not Start | Improper starting procedure, No fuel, Low battery output, Excessive resistance in starting circuit, Crankcase oil too heavy, Improper type of fuel, Water, dirt, or air in fuel system, Clogged primary fuel filter element, Clogged secondary fuel filter element | See starting section of this manual. Take special note of Bypass Switch operations., Check level of fuel in fuel tank., Check electrolyte level and specific gravity of battery., Clean and tighten all battery connections., Use oil of proper viscosity., Consult fuel supplier and use proper type of fuel for operating conditions., Drain, flush, fill, and bleed system., Clean or replace filter element. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Engine overload, Intake air restriction, Clogged primary fuel filter element, Clogged secondary fuel filter element, Improper type of fuel, Overheated engine, Below normal engine temperature, Improper valve clearance, Dirty or faulty injection nozzles, Injection pump out of time, Turbocharger malfunction. See the table for the matching fixes.
Documented causes: Below normal engine temperature, Clogged primary fuel filter element, Clogged secondary fuel filter element, Water or dirt in fuel system, Dirty or faulty injection nozzles, Air in fuel system, Improper type of fuel. See the table for the matching fixes.
Documented causes: Engine overloaded, Low coolant level, Cooling system needs flushing, Defective thermostat, Defective temperature gauge/sender. See the table for the matching fixes.