I was listening to the radio the other day while parked and had the truck in the ON position without the motor running and the Check Engine Light caught my attention because it blinked 8 times then went solid. No audible warnings of any kind, just blinks 8 times then turns solid then turns off completely once I crank the engine. No CEL warnings during normal driving either.

I have a 2008 F-150 XL RWD 4.2L V6.

I searched Google and came upon dozens of threads other people posted with similar issues. The common explanation given was that it's a misfire causing the CEL to blink and that you should hook it up to a scanner to read any codes ASAP.

So I hooked up my basic little Actron CP9550 OBD scanner and it shows "no readable codes."

A few incidental things I have done to the truck lately:

I did an oil change recently because while checking the oil level and condition I noticed the oil filler cap had a somewhat strong fuel smell to it which I never recall it having before. So I opted to change the engine oil and oil filter immediately. I chalked up the fuel smell in the oil due to the fact that I haven't driven the truck but for short in-town trips for over 6 months. I figured the fuel smell was likely due to not running the engine at temperature and not being able to burn off the combustion mixture.

At any rate, I felt I should do a complete engine oil change just in case because it may be a more major problem like large amounts of fuel getting dumped into the oil. My plan was to keep a close eye on it just in case it was something more major like a stuck open fuel injector and if it continued I was going to ship an oil sample to Blackstone Labs for analyses. But with this blinking CEL it's got me a bit worried that this may be a more immediate problem that can't wait.

Another note, I changed out a faulty oxygen sensor that was throwing bad OBD codes last year, cleared the codes with my OBD scanner and haven't had any check engine lights come on during normal driving since, only this ON position blinking.

I changed the fuel filter shortly after changing the faulty HO2 sensor because it was time to change that too.

I pulled the truck battery and put it on a trickle charger during last year's brutal winter but it has been back in the truck all summer now.

I mounted a new set of tires just yesterday and I haven't reset the TPMS yet, could that be related to the flashing CEL? Probably not.

I did notice a small leak, more like a "weeping" oil mist around the left passenger's side valve cover gasket. It's just enough oil to attract fine dust and that's the only reason I could tell it was weeping oil at all. The driver's side valve cover gasket is entirely clean of any oil though. The truck has 60,000 miles on it and I haven't changed the original spark plugs or coil pack.

Lastly, would using the "clear codes" option on my OBD scanner reset things and maybe make the OBD-II system throw codes that haven't appeared yet? It's odd that a blinking CEL, even if it only happens in the ON position would not result in any readable OBD codes. Could it be that my sensor isn't advanced enough to read certain codes or certain in depth information? I'll try to borrow my neighbor's scanner to see if that's the problem. I doubt it though even a basic scanner should be able to read all if not most OBD codes.

Anyway, sorry for the long winded question, I'm just trying to provide as much information as I can to shed light on what the problem might be.

 

This is what the Ford manual says in regards to a CEL flashing 8 times while in the ON position:

"If the vehicle’s engine or transmission has just been serviced, or the
battery has recently run down or been replaced, the OBD-II system may
indicate that the vehicle is not ready for I/M testing. To determine if the
vehicle is ready for I/M testing, turn the ignition key to the ON position
for 15 seconds without cranking the engine. If the
indicator blinks eight times, it means that the vehicle is not ready for I/M testing; if
the indicator stays on solid, it means that the vehicle is ready for
I/M testing.

The OBD-II system is designed to check the emission control system
during normal driving. A complete check may take several days. The
vehicle is not ready for I/M testing, the following driving cycle consisting
of mixed city and highway driving may be performed:
15 minutes of steady driving on an expressway/highway followed by 20
minutes of stop-and-go driving with at least four 30-second idle periods.
Allow the vehicle to sit for at least eight hours without starting the
engine. Then, start the engine and complete the above driving cycle. The
engine must warm up to its normal operating temperature. Once started,
do not turn off the engine until the above driving cycle is complete. If
the vehicle is still not ready for I/M testing, the above driving cycle will
have to be repeated."

Something tells me I shouldn't drive the truck at all even though the manual seems to state the procedure to overcome a vehicle "not ready for I/M testing" is to drive it to "is ready for I/M testing" status.

 

Drive it, there's nothing wrong with it. This is NOT a fault condition, it is advisory only. The 8X flashing KOEO MIL simply indicates that your truck's system hasn't completed all the internal OBDII self-tests. Unless you have an upcoming emissions test, forget about it.

Yes, that would cause the whole self-test cycle to start over from scratch, same as if the battery were disconnected or if the fuse that supplies keep-alive power to the PCM's memory is blown.

See if it can display OBDII readiness monitors. That will tell you which subsystem(s) are not completed.

 

Thank you for the reply and the advice. I took the truck for a spin today, and went through the OBD-II driving cycle procedure. I also drove the truck high speeds to hopefully burn off combustion deposits. So I got home and did the whole KOIO 15-second test and the blinking CEL light disappeared.

I also hooked my OBD scanner to the truck and looked at the I/M test subtypes like you suggested, everything read "READY" except the evaporative system, it read "NOT READY." No CEL is coming on during normal driving so... just ignore that I/M "not ready" subtype reading?

Thanks for the help, I appreciate it.

 

You generally need a specific number of driving cycles for all systems to be in READY state. Sorry, don't know what that number is.

 

The evap monitor can be stubborn. It's usually the last one to achieve readiness.