I got an obdII code on 02 escort P0403. My 4th piston is misfiring. What would that be?

Question

sounds like a low oil problem but oil is full and less than 2,000 miles old

Answer 1

Before thinking your engine is ruined it is possiable to be a hydralic lash adjuster and yes they are used on overhead cam engines.The code you gave is for a EGR  and not likely that on your engine it would cause a 1 cylinder misfire.Only known that to be on the Windstar engines V6.

Have amechanic or someone that knows  a car well and remove the valve cover/cam cover and inspect it.

Hope this helps.

Answer 2

Don't know where you got your info. but PO403 is exhaust gas recirculation circuit malfunction.

Answer 3

I'm assuming you mean P0304, NOT P0403. I'm sorry to be the bearer of bad news, but it sounds like you need to evaluate much this car is worth putting money into. The reason for this, is because cylinder number 4 has dropped a valve guide causing low compression from damage to the head, valves on cylinder #4, and the piston. This is almost ALWAYS the cause of cylinder #4 'dead' or 'low' on the 2.0L SPI engines (eighth digit of VIN 'P') on Escort/Tracer/Focus vehicles. That said, you will need to replace the cylinder head, and damaged piston(s) to repair. By the time you do the math to figure out the cost, you will be far further ahead to replace the entire engine assembly with a used or rebuilt engine. Hope this helps.

ADDED: All this is provided that everything in the ignition system (coilpack, wires, spark plugs) has been ruled out.