Fuel system is also a detection object of OBD system, but fuel quality will not bring obvious effect to the OBD diagnosis. OBD mainly focuses on emission. But fuel with poor quality or which can not meet the standard (requirement of percent of sulfur, olefin and aromatic hydrocarbon) will accelerate the failure of catalytic converter and oxygen sensor, or knot the nozzle and the inlet, and these may affect the precious of the air-fuel ratio and bring high emission.
Tough fuel with poor quality will not affect the OBD function in short term but it may make the MIL bright at an earlier time.
Meanwhile, fuel with poor quality also effect the engine and cause more consumption.
The engineer suggests, after travel more than 30000 kilometers, it is better to clean the oil passage or add fuel additives to improve the performance of the oil.