Tech Tips
Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.
Inspect the fuses and relays related to this system before inspecting the suspected areas below.
| Symptom | Suspected Area | Link |
|---|---|---|
| Engine does not crank (Does not start) | Battery | |
| ST NO. 1 relay | ||
| Starter assembly | ||
| VC output circuit (ECM 5 V output) | ||
| Starter signal circuit | ||
| Entry and start system (for start function) | ||
| No initial combustion (Does not start) | Immobiliser system | |
| ECM power source circuit | ||
| VC output circuit (ECM 5 V output) | ||
| Crankshaft position sensor | ||
| VVT sensor (for intake camshaft) | ||
| VVT sensor (for exhaust camshaft) | ||
| Camshaft position sensor | ||
| Fuel pump control circuit | ||
| Ignition system | ||
| Valve timing | ||
| Starter signal circuit | ||
| ECM | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Engine cranks normally but difficult to start | Fuel pump control circuit | |
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Engine coolant temperature sensor | ||
| Ignition system | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| Compression | ||
| Intake system | ||
| Throttle body with motor assembly | ||
| Engine difficult to start | ||
| PCV hose | ||
| Starter signal circuit | ||
| ECM power source circuit | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Incomplete intermittent combustion occurs (Does not start) | Fuel pump control circuit | |
| Ignition system | ||
| Fuel line | - | |
| Fuel pump assembly (for low pressure side) | ||
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| Crankshaft position sensor | ||
| VVT sensor (for intake camshaft) | ||
| VVT sensor (for exhaust camshaft) | ||
| Camshaft position sensor | ||
| Valve timing | ||
| Starter signal circuit | ||
| ECM power source circuit | ||
| High engine speed | Air conditioning signal circuit | |
| Throttle body with motor assembly | ||
| Intake system | ||
| Engine coolant temperature sensor | ||
| PCV hose | ||
| PCV system | ||
| ECM power source circuit | ||
| Low engine speed (Poor idle) | Fuel pump control circuit | |
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Throttle body with motor assembly | ||
| Intake system | ||
| PCV hose | ||
| Engine stalls on deceleration | Idle speed (refer to "Low engine speed" symptom) | |
| Rough idle | Rough idling | |
| Compression (engine mechanical) | ||
| Air fuel ratio sensor | ||
| Heated oxygen sensor | ||
| Mass air flow meter sub-assembly | ||
| Ignition system | ||
| Air conditioning signal circuit | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| Fuel line | - | |
| Fuel pump assembly (for low pressure side) | ||
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Intake system | ||
| Electronic throttle control system | ||
| PCV hose | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Hunting (Poor idle) | Electronic throttle control system | |
| Intake system | ||
| ECM power source circuit | ||
| PCV hose | ||
| Mass air flow meter sub-assembly | ||
| Air fuel ratio sensor | ||
| Drive start control system | ||
| Hesitation/Poor acceleration (Poor driveability) | Fuel line | - |
| Fuel pump assembly (for low pressure side) | ||
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Spark plug | ||
| Ignition system | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| ECM power source circuit | ||
| Mass air flow meter sub-assembly | ||
| Valve timing | ||
| Throttle body with motor assembly | ||
| Air intake control circuit | ||
| Knock control sensor | ||
| Compression (engine mechanical) | ||
| Brake override system | ||
| Drive start control system | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Lack of power | Lack of power | |
| Surging (Poor driveability) | Spark plug | |
| Fuel line | - | |
| Fuel pump control circuit | ||
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Ignition system | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| ECM power source circuit | ||
| Mass air flow meter sub-assembly | ||
| Variable Valve Timing (VVT) system | ||
| Compression (engine mechanical) | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Engine stalls soon after starting | Fuel pump control circuit | |
| Fuel pump assembly (for low pressure side) | ||
| Fuel pump with seal sub-assembly (for high pressure side) | ||
| Fuel line | - | |
| Spark plug | ||
| Ignition system | ||
| Port fuel injector assembly | ||
| Direct fuel injector assembly | ||
| ECM power source circuit | ||
| Mass air flow meter sub-assembly | ||
| Throttle body with motor assembly | ||
| Engine stalls | ||
| Intake system | ||
| PCV valve and hose | ||
| Compression (engine mechanical) | ||
| No. 1 valve rocker arm sub-assembly* | ||
| Engine stalls only during air conditioning operation | Air conditioning signal circuit | |
| ECM | ||
| Unable/difficult to refuel | Fuel system (canister, refueling valve, roll over valve, fuel tank, etc.) | - |
| MIL (malfunction indicator lamp) malfunction | MIL Circuit | |
| Meter/Gauge system | ||
| Exhaust sound does not change | Exhaust Gas Control Circuit |
Tech Tips
*: Check "Fuel Cut Elps Time" in the Data List. If the elapsed time is over 0 sec, then the engine speed is high (the engine speed at which fuel cut occurs + 500 rpm or more). In this situation, there is a possibility that a No. 1 valve rocker arm sub-assembly will become loose and malfunction, check that the No. 1 valve rocker arm sub-assemblies are properly installed.