Ford Trouble Codes P0125, P0401, P0303 and P0316
DennisB WiseAutoTools.com © Summary: Ford CEL’s (Check Engine Light’s) can be triggered for many reasons. It’s best to scan for codes as quickly as possible and get the problem resolved. Ignoring, problems may cause other ones in the long term. Below is a question from a reader from a different one of my articles.
Question – I have a 2003 Expedition 4.6 these are the codes I am getting; P0125, P0401, P0303 and P0316. I Changed #3 and #4 ECM and EGR. What else could it be? I am thinking of changing DPFE but not sure if I should spend the money. I’ve also have heard that it’s best not buy the aftermarket one. Can I please get some help this truck is costing me!
Answer – Matt, the ECM (Electronic Control Unit) also known as the vehicle’s computer, hardly ever fails and there’s not one per cylinder. I’m thinking you meant to say #3 and #4 coils. That would have made more sense. As far as the EGR – like my original article points out (about Ford EGR Low Flow) EGR low flow is usually because of intake ports clogged NOT a faulty EGR. Along with restricted EGR ports in the intake, the DPFE is also a very common cause of the P0401 code. The P0125 has to do with the engine not reaching operating temperature quick enough to meet the computer’s predetermined “parameter” or specifications. I would check the coolant level and the thermostat operation. If the coolant is low find out where it’s going… leaking? burning is a cylinder? Is the thermostat allowing the engine to heat up quickly before opening and allowing coolant flow? Matt. The P0401 is covered in the repair article linked above in more detail. The P303 is a misfire code for the #3 cylinder. Misfires for particular cylinders are usually caused by a bad coil or spark plug. A mechanical issue like low compression (from worn rings or valves) could also cause a misfire code for one cylinder. If in doubt I would do a compression test and maybe a leak down test. We have the tools to do this if you need to purchase them. The P0316 means that the computer is seeing a lot of misfires when the engine is first started up. Excessive misfires within the first 1,000 revolutions will trigger the P0316 fault code. I would concentrate on the P0125 and the P303 first. After fixing the problems causing those codes I would recheck. At least the P0316 should be taken care of when the number three misfire code is taken care of. Not sure why you would have changed the #4 coil since there was no fault code for that cylinder.
Aftermarket DPFE – In the past I’ve seen Ford OEM (Original Equipment Manufacturer) parts re-boxed and sold as aftermarket one from a parts store. I’m not sure if any of the parts stores still do that. In all likelihood today, the parts are probably going to come from China. The fact is that China is that many times they are very good at taking our products and “backwards engineering” them. They produce very good quality in many cases and can sell at very low prices. If I were purchasing a DPFE today, I would check to see what the price difference is between the dealer and several parts stores. Keep in mind that the parts stores may actually offer a better/longer warranty than the dealer. Also the labor involved to change a DPFE is minimal, so if it had to be changed out again, there’s no great loss of time. Good Luck.