DRIVETRAIN: 5.4 EFI, automatic transmission, 4X4
MILEAGE: 90,412
COMPLAINT: "Service Engine" light on.
(All photos: Curt Marsh) Having more than one brand of scan tool is good, if you remember to use them.
"Hi. How can I help you?" I said as the customer walked up to the counter.
"Well, my truck needs a tune-up. When can you do it?"
I asked the question that I always ask when someone says that his or her vehicle needs a tune-up: "Are you having any trouble with the way it runs?"
"No, it runs great, but I think it's time," he responded. "The ?Service Engine' light is on."
I was all ready to launch into my "a tune-up probably won't cure what's causing the light to be on" speech when he said that the truck had 90,000 miles on it and had never had a tune-up. Okay, time to modify the speech: It probably needs a tune-up, but that, in and of itself probably won't turn off the light.
Business was slow, and we didn't have much in the appointment book, so I asked if he could leave it. It was early afternoon, and we had a couple of jobs started, so I told him that it was possible that we might not get it all done that day. I would rather not have to make that dreaded 4 o'clock phone call if I don't have to. This Ford truck has Coil-On-Plug (COP) ignition, and some of the plugs are buried, so it would take some time. The diagnostics after the tune-up might not be very simple either. He said that he could leave it overnight, but that he would definitely need it by the next evening.
Let's get started When we pulled the truck into the shop, sure enough, the Malfunction Indicator Light (MIL) was glowing. While the preliminary tune-up inspection -- belt, hoses, fluids -- was performed, I connected a scan tool to pull the codes and check the freeze frame data. I checked both the generic and the manufacturer specific memories. I retrieved a P0125 and P1000.P0125 is "insufficient coolant temperature for closed-loop fuel control." It is stored if the Engine Coolant Temperature (ECT) sensor does not indicate that the engine has achieved the required temperature level to enter closed-loop operation within a specified amount of time after starting the engine. P1000 -- monitor testing not complete -- is stored until all the monitors have been run after the codes and freeze frame data have been cleared.
When I checked the freeze frame data, the scanned ECT value was showing -40
