Check Engine Light on But No Codes

[angelo49]

https://www.google.com/url?sa=t&rct...xplorer_2000&usg=AOvVaw3KYKpeJrRBaS5sz5WJWIrF
Hi,
Check Engine Light came on. 2009 Ford Explorer 4.0 xlt
Code reader turns up NO Codes, it just cycles through showing dashes (----) but no letter or numbers and will not reset.
I also notice that the Average MPG seems to be stuck around 16.5 mpg no matter the driving condition. I know the mpg would change while driving, but this rarely moves.
Any ideas???
Thanks,
Angelo

 

[Rcflyer330]

What code reader are you using? Did you cycle the key and did the light go away?

Also when was the last time you reset the mpg screen? I dont know how long the averege calculates for ( how many miles or some other measurement) but i do know the calculated miles for the tank calculates off of the past 1000 miles average.

 

[angelo49]

It's a cheap HF reader. I got the truck last June and only put about 1,800 miles on it.
I don't know about 'cycle the key' and never reset anything. The truck runs great even with the CEL on and inspection is due next month.
Thanks,
Angelo

 

[Blue m&m]

Have you tried pulling the negative battery cable to reset the computer?

 

[15Limited]

Have you tried pulling the negative battery cable to reset the computer?

OP...he’s suggesting you disconnect the Negative cable from the battery for 30 minutes, then reconnect to see if your computer will reset.

 

[angelo49]

I'll try the battery disconnect if autozone doesn't find anything
Angelo

 

[Tech By Trade]

Grab a ford compatible ELM327 and forscan. It will tell you whats going on, and even go back and show you all the alarms that have ever been cleared.

 

[angelo49]

Today I just went ahead and disconnected the negative battery terminal for about an hour.
Connected and started and there is NO CHECK ENG. LIGHT.
If it IS going to come back on, how long, or how many miles will that take??
Angelo

 

[BenSantos]

That is a hard question to answer. When checking for the reoccurrence of an OBDII related DTC you need to take the vehicle through a "drive cycle". In most cases if a repair has been made, the codes have been reset, a drive cycle is completed, all of your readiness monitors have passed and your engine light is not on then you are most likely good. But since you are saying that there are no OBDII codes stored in the computer it is hard to say when you can assume that your "safe". A few thoughts on what the problem might be and what to check:

1. One thing that you should check (if it is possible with your reader) is the MIL status. This will tell you if the engine light should even be on. On rare occasions, the wiring shorts to power and it gives a false light.
2. There are generic DTCs and manufacturer specific DTCs. I have never seen it before, but it is possible that you have a manufacturer specific DTC and your code reader just can't see it. You would need to have a better, or Ford specific, scanner.

Since the light is not on at the moment I would suggest driving it for a few days (highway and street, start with a full tank) and see what happens. This is usually enough time to complete a drive cycle. Will your code reader show you the readiness monitors? If it does, keep checking to see if they all show "pass" (some might say N/A, ignore those). If they have all passed and your light is not on then you will most likely pass emissions.

As far as the MPG goes I agree with Rcflyer330, if you do the same driving every day and you don't reset the counter you might not notice a difference in average MPG.

 

[angelo49]

Did the battery disconnect reset the MPG ??
If not how is that done?
Thanks
Angelo

 

[BenSantos]

Pulling the battery cable should have done it. If not, this is the procedure from the owners manual:

Press and release the SELECT/RESET control switch to scroll and reset the following functions (odometer, distance to empty, average fuel economy). Select or reset the function by holding the SELECT/RESET button for more than two seconds.

If you don't have it, here is a link to your owners manual http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/09expog3e.pdf the above procedure is on page 121.

 

[angelo49]

OK! I do have the owners manual.
Thanks
Angelo

 

[angelo49]

Hi,

I disconnected the battery and reset the engine light.

After about 65 mi. the light came back on.

Advance Auto pluged in and came up with a PO128 code.

P0128 Coolant Temperature Below Thermostat Regulating Temperature.


Angelo

 

[Rcflyer330]

Time for a new thermostat from that code. Does your scanner do live data if so look at your coolant temp. Full operating temp should range between 190 deg f to 210 f. Start from a cold start and the temp should get to operating temp within lets say 5 miles. You may want to think about getting the aluminum thermostat housing at the same time since its prone to leaking.

 

[Blue m&m]

Could be a fail safe thermostat that is stuck open.

 

[angelo49]

I did notice that the truck runs cold. The needle would reach just to
the low range on the gage. could be stuck open.
Angelo

 

[Rcflyer330]

Yes it can get stuck open. Mine did last year and it was a motorcraft part that replaced my original that was staying closed too long.