What is the problem my 2001 mercury grand marquis The check engine light came on and car sputtering you changed fuel filter put injector cleaner in but it did not work?

Since the check engine light is on and the fuel filter and injector cleaner haven't solved the sputtering problem, the issue is likely more serious than clogged fuel lines or injectors. You *must* get the diagnostic trouble codes (DTCs) read from your car's computer. This can be done inexpensively at most auto parts stores (like AutoZone, Advance Auto Parts, etc.). They'll plug a scanner into your car's OBD-II port and retrieve the codes.

The codes will give you a much better indication of the problem. Possible causes based on your description, *assuming the codes haven't been checked*, could include:

* Spark plugs/wires: Worn or faulty spark plugs or ignition wires can cause misfiring and sputtering.

* Ignition coil: A failing ignition coil can prevent one or more cylinders from firing correctly.

* Mass airflow sensor (MAF) sensor: A dirty or faulty MAF sensor provides inaccurate information to the engine computer, leading to poor fuel mixture and sputtering.

* Oxygen sensor(s): Faulty oxygen sensors can disrupt the air/fuel mixture.

* Catalytic converter: A clogged catalytic converter can restrict exhaust flow, causing engine performance issues. (This is less likely to cause sputtering alone but more of a general performance issue).

* Crankshaft Position Sensor (CKP) or Cam Position Sensor (CMP): These sensors are crucial for engine timing; a faulty sensor will cause significant problems.

* Throttle Position Sensor (TPS): A faulty TPS might be providing incorrect information to the engine control unit (ECU).

Do not continue driving the car extensively with the check engine light on. Ignoring the problem could cause further damage. Get those codes read – that's the first and most crucial step in diagnosing the problem.