Why is the Hino 700 engine malfunction indicator light on?
2 Answers
The engine malfunction indicator light may illuminate due to the following 7 main reasons: Sensor failure: This includes sensors such as coolant temperature, crankshaft position, air flow, intake air temperature, and oxygen sensors. When these sensors are damaged, have poor contact, or experience signal interruption, the vehicle's ECU cannot accurately obtain engine data, triggering the malfunction indicator light. Fuel/oil quality issues: Failure to use the manufacturer-recommended fuel and engine oil may cause engine wear, leading to the illumination of the malfunction light. Poor fuel mixture combustion: This can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the malfunction light will activate as a warning. Causes include spark plug failure, ignition coil malfunction, fuel pump issues, or fuel line blockage. Turbocharging problems: Issues with the intake boost system or turbocharger can trigger the light. The most common is turbocharger damage, often accompanied by oil leaks, excessive oil consumption, power loss, metallic noises, or blue/black exhaust smoke. Intake system problems: Air intake issues may lead to engine pipe blockages, potentially triggering the light. A dirty air filter that hasn't been regularly cleaned can cause intake problems. Exhaust system faults: These can also activate the light. Common causes include rear oxygen sensor failure, catalytic converter issues (most frequent), or exhaust camshaft/bearing problems. Leaded gasoline, improper lubricant additives, physical damage to the catalytic converter, or fuel system malfunctions often cause catalytic converter failure. Anti-theft system malfunction: If the electronic anti-theft system fails or the anti-theft controller doesn't match the engine ECU, the system may prevent normal engine operation while illuminating the malfunction light. When the engine malfunction light illuminates, follow these steps: First check if the engine operates normally. If there's shaking, black smoke, etc., avoid restarting. Never restart if the red warning light is on. If the engine starts, turn it off for 5-10 minutes. Then without pressing brakes (or clutch for manual transmissions), activate the ignition to ON position to initiate self-diagnosis. After 5-10 seconds, check if the light turns off. If the light remains on, visit a service center immediately. Technicians can use diagnostic tools to read trouble codes and perform targeted repairs.
That day, the engine warning light on my Hino 700 dashboard suddenly came on. As an experienced driver, my first reaction was to pull over immediately and inspect the vehicle. Possible causes could be a loose or faulty sensor, such as an oxygen sensor detecting abnormal emissions, or clogged fuel injectors in the fuel system leading to incomplete engine combustion. It might also be due to a blockage in the emissions after-treatment system like the DPF (Diesel Particulate Filter), which is common in diesel vehicles. Short-distance driving can accumulate carbon deposits, triggering the warning light. I recommend turning off the engine, waiting a few minutes, and then restarting it. If the light remains on, use an OBD scanner to read the fault codes, which can accurately pinpoint the issue. Don’t push through and continue driving, as this could damage the engine or result in fines for exceeding emissions limits. Regular maintenance like oil changes and DPF cleaning can prevent such issues, ensuring driving safety and prolonging the vehicle’s lifespan.
