A 2000 kia sportage of a customer initially was setting and airflow sensor code. I verified the wiring integrity and found that everything related to that was ok. Hence, I told him to replace the sensor which he did and said he has noticed remarkable changes in the car now. However, the car is still misfiring and setting up a confirmed P0303 code. Please what could be responsible for this.
I cleared the code, check light went off and within few minutes the check light came back on. He told me he has replaced all the 4 injector and coils with a new one. But the spark plugs were fairly new. Is late that's why I can't verify everything. Please as a guide what would've caused that?