What is the reason for the 'Check Engine' light appearing after starting the Bestune T77?
2 Answers
Possible reasons for the 'Check Engine' light appearing after starting the Bestune T77 are as follows: 1. Issues with the car's engine cooling system; 2. Thermostat failure; 3. Problems with the oxygen sensor; 4. The vehicle's exhaust emissions do not meet standards; 5. Issues with the gasoline, etc. Here are the solutions: 1. Determine if the engine is working properly by checking the long-term and short-term fuel trim values and the injection pulse width. 2. Determine if the engine is working properly by checking the oxygen sensor's output voltage and change frequency. 3. Diagnose car faults through exhaust emission test data.
Last time my car also showed this warning light, and after checking, it turned out to be a fuel quality issue. The yellow light came on after filling up with cheap gas from a small gas station. The mechanic said poor-quality gasoline can cause the sensor to give false alarms. Another common situation is the fuel cap not being tightened properly—vacuum leaks can trigger a fault code. Of course, it could also be a real engine problem, such as aging spark plugs causing misfires, a faulty oxygen sensor, or a clogged catalytic converter. But don’t panic just yet—try resetting the system by disconnecting the battery: remove the negative terminal, wait ten minutes, and reconnect it. The light might disappear after the system resets. If it doesn’t go away, go read the fault code—a repair shop can diagnose the specific issue for just fifty bucks.
