Why does the MG TCM request illuminate the engine fault light?
2 Answers
The engine fault light may illuminate due to the following 7 main reasons: Sensor malfunction: Sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors may be damaged, have poor contact, or experience signal interruption, preventing the vehicle's ECU from accurately obtaining engine data, which triggers the engine fault light. Fuel or oil quality issues: Failure to use the fuel or oil as specified by the manufacturer may cause engine wear, leading to the illumination of the fault light. Poor combustion of the air-fuel mixture: Poor combustion can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the fault light will illuminate as a warning. Issues such as spark plug failure, ignition coil failure, fuel pump failure, or fuel line blockage can all lead to poor combustion. Turbocharging problems: Issues with the intake turbocharging pipeline or turbocharger can also trigger the engine fault light. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: If the vehicle's intake system is compromised, it may lead to engine pipeline blockage, and in severe cases, the engine fault light will illuminate. A dirty or uncleaned air filter can cause intake problems. Exhaust problems: Exhaust system faults can also trigger the engine fault light. Common causes include rear oxygen sensor failure, catalytic converter issues, exhaust camshaft or bearing failure. The catalytic converter is the most frequent culprit, often damaged by leaded gasoline, lead or silicon-based lubricant additives, physical impact, or fuel system malfunctions. Anti-theft system malfunction: If the vehicle's electronic anti-theft system fails or if the anti-theft controller does not match the engine's electronic controller, the anti-theft system may prevent the engine from operating normally, accompanied by the illumination of the engine fault light. If the engine fault light illuminates, follow these steps: First, check if the engine is running normally. Look for symptoms such as shaking or black smoke. If present, avoid restarting the engine. Note: Do not restart the engine if the red warning light is on. If the engine can start, turn it off and wait 5-10 minutes. Without pressing the brake, press the start button once or turn the key halfway to the 'ON' position without depressing the clutch. The vehicle will enter self-check mode. After 5-10 seconds, observe if the fault light turns off. If the fault light remains on, visit a service center as soon as possible. Technicians can use a portable diagnostic tool to read the fault codes, identify the issue, and perform targeted repairs.
I've noticed many MG owners encounter the issue of the TCM request illuminating the engine malfunction light, typically caused by the transmission control module detecting anomalies such as sensor failures, circuit shorts, or software errors. I experienced a similar situation once when the oil pressure sensor was faulty, and the module signaled through the data bus to light up the malfunction indicator, warning of potential risks. I recommend immediately using an OBD scanner to read the fault codes, with common codes like P0700 pointing to transmission issues. Don't delay too long, as it could worsen transmission damage. Additionally, check the battery voltage and wiring harness connections to avoid electrical interference. If you lack the tools, promptly visit a professional workshop for inspection—don't ignore this warning.
