I made an appointment for an oil change since it was due and I was going out of town on the highway a few days later so having the vehicle checked over is a good thing. I took the truck to the dealer early in the morning and I should mention it had and was very cold here for several days with the temps down to -30C overnight. I left the truck with the dealer and went to work. Received a call that the truck was ready and that the service engine soon light was on and would I like to have it checked for $80? As well there was some seepage around the master cylinder. I advised the service rep that the light was not on when I dropped it off and I would drive it for a few days to see if the light would go off. I thought perhaps it had something to do with the extreme cold and the truck being inside where it was warmer and may have caused something to thaw partially. I should mention that I also replaced my battery a few days before as the original was dead and I didn't want to be out on the highway with a dead battery. I gassed up; made certain the gas cap was on tight and drove on the highway 3 1/2 hours for a weekend away. Terrible fuel consumption; 3/4 of a tank for a 3 1/2 hour drive. I usually can drive that distance on less than 1/2 a tank. Thought it could be the cold and the fact the truck hadn't been on the highway for a couple of months. After driving home again the engine light is still on however I did get better mileage coming home. The cruise control didn't work and I am thinking that is a result of the seepage from the master cylinder although the dealer mentioned nothing of that. Again I thought that was from the cold. I am going to call them tomorrow about the engine light since they are very concerned about getting a good response on the survey they sent. Any thoughts? I thought perhaps disconnecting the battery again to clear the engine light.

 

Please post year, make, model, engine, transmission for starters.
Find out the error code that is triggering your "service engine soon" light and we might be of some help to you. Did your dealer say what it was? Places like Autozone, Advanced Auto Parts and a great many others will connect their diagnostic tools to your machine & tell you the codes, for free.

 

Sorry, I forgot the vehicle specs. 2002 F150, 4.6l, 2x4 Super cab.
The dealer didn't do the scan since I wasn't prepared to pay for it and I think they did something or something happened while it was in their shop for the oil change. I'm hoping they do the scan for free.

 

Most auto parts stores will read the codes for free.

 

If the pressure sensor on the end of the master cylinder is leaking, it's a fire hazard. A $30 fix.
If the cruise control does not work, that sensor may be open circuited when it should be closed. This sensor knocks the cruise control off when you hit the brakes by opening the circuit to the controller..
A cruise control test from the steering wheel would give you a flash code to relate the fault to.
As to the CEL code, you need the code first.
Do not begin trying to justify issues based on the outside temp.
When you have issues they have to be found and repaired.
One thing you need to know is when you changed the battery, the computer rebooted and lost all learned table info.
Being very cold will use more fuel on top of the reboot.
Air gets heavier as the temp drops so needs more fuel to keep the air/ fuel ratio correct as determined by the Oxygen sensors.
You can't do anything about it.
Good luck.

 

Be sure your truck was not under the recall for that pressure switch. If so Ford will cover it. It is a simple normally closed switch. If you pull off the connector you can check for continuity at the switch. It should be closed and then go open when the brake pedal is applied. If that switch is weeping brake fluid you should unplug it until it is fixed. It is hot even with the truck off and parked.

$80 bucks to check for codes? You can buy a code reader these days that will work for for most CEL trips...tell you the code...basic description....has erase function, freeze frame... They are nothing like a scanner at a dealership that read ABS codes, body and chassis codes, but for the most part they are adequate for us guys.

I know when we get those -20 temps I will sometimes get a CEL. It only happens when my truck sits outside all night in that cold (plugged in) and one of my commercial accounts calls that has heated parking in the bus bays...so I pull my truck in. When I start it up after it has been in that warm area the CEL comes on. Every single time I pull the code it is for the pressure sensor in the fuel tank. That is the sensor that trips a CEL if the cap is not on....but mine is. I clear it and it is fine until a situation like that occurs again....dunno.

 

An update on my post. I took the truck back to the dealer's service department and they agreed to check it out for free since I was not pleased with the service I had the week before. You shouldn't go for an oil change an leave with problems. Anyway they checked the seeping at the master cylinder and indicated the valve needed replacing as the seal had failed. No problem there. They checked for codes and there was nothing showing and decided that the technician must have started the truck with air cleaner removed and the truck sucked in too much cold air and affected the air sensors. Who knows. I have a feeling the tech guy was not that experienced. All is now good and I will have to watch for a code reader on sale for future.

 

I'm glad all is good. Not quite sure about the air cleaner story....LOL. No code and the CEL was on? Not sure on that one either.....anywho...glad all is OK..

 

The mechanic may have disconnected the MAF sensor connector near the air filter housing and forgot to reconnect before starting the truck. It would trigger a code.