How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Dan Your Own Question

Dan
Dan, Automotive Management
Category: Car
Satisfied Customers: 624
Experience:  36 Plus Years of Direct Automotive Experience
Type Your Car Question Here...
Dan is online now
A new question is answered every 9 seconds

2002 Subaru Outback: The check engine light..next time..gas cap

Customer Question

The check engine light on my 2002 Subaru Outback will come on occasionally. One time it will come on and then the next time the car is started it doesn't. The gas cap has been checked per owner's manual. It has to get from So. Cal to Wyoming (1500 miles) is it okay to drive that distance before getting it into a mechanic?
Submitted: 7 years ago.
Category: Car
Expert:  Dan replied 7 years ago.

Good Morning!

I recently read some information regarding this issue. Please read it, it answers a lot of questions regarding the warning lights and "check engine lights". Basically, sometimes these lights mean nothing but it always a good idea to make sure the basic are checked, oil, water and all other fluids.

The Dreaded Light

Illuminating the mystery of the "check engine" light

By PHIL COCONIS

My, how times have changed. Back in the days when leaded fuel was sold at "service stations," as they were quaintly called, motorists had to be concerned with only a few warning lights that each monitored the condition of an important vehicle system. Colorfully dubbed "idiot lights" by the gauge-reading contingent, these did little more than indicate it was time to get your car off the road as soon as possible. Today's instrument panels, however, display a Christmas tree of warning lights that provide a wealth of information (some might say too much). Question is, what do those lights all mean? Are life, limb, and property at risk if you continue to operate your vehicle? And isn't it going to take a lot more than an idiot to interpret them all?

Warning Vs. MIL
There are two types of instrument panel displays that bear explanation here: Warning Lamps, and Malfunction Indicator Lamps (MILs). Warning Lamps generally report on a single specific component or subject, such as fluid levels (coolant, windshield washer fluid, fuel, engine oil, etc.), instrument gauges (if reading abnormally high or low) and the position of the emergency/parking brake, doors, trunk lid, and the like. These lamps are generally red in color.

The MIL, on the other hand, refers to a more complicated system monitored by a processor (computer). It usually requires testing by a service professional to determine the exact nature of the malfunction and the repair required. These systems include the antilock braking system (ABS), airbag system (SRS), automatic transmission/transaxle, traction control, and the Engine Management/Emission Control system (which we'll cover in a bit more detail). These lamps are generally amber in color, and will appear as a descriptive icon or as the initials of the system they support. Something else that they all have in common is that they will illuminate when the ignition key is first turned on, and will stay illuminated momentarily after the engine is started.

During this period, all of these computer-monitored systems are going through their programmed self-test procedures, so it's not uncommon for them to stay on for a few seconds, and then go off after passing the internal diagnosis. If any of them stay on, or come back on after momentarily going off, that indicates a problem with the system.

The "Check Engine" lamp, as it is commonly known, may actually appear using these words, or may appear as "Service Engine Soon," or a descriptive icon (such as an engine). When it is illuminated, the problem could be in one of three areas: Engine Management, Emission Control, or Accessories. Although they are distinct subsystems, the same computer controls them all.

Subsystems
Engine Management: This system is directly responsible for the fuel delivery and ignition/spark requirements of the engine, and uses a number of sensors, which input into the computer, so that it can make adjustments for optimal performance.

Emission Control: This system is closely integrated with the engine management system and reduces exhaust and evaporative emissions, while maintaining optimal driveability.

Accessories: Only recently have some of these components been assigned control by the engine management computer. They include the fuel pump, alternator, air conditioning compressor, and radiator cooling fan.Bottom of Form

All of these components are designed to operate with certain parameters that the computer monitors. When one of the components operates outside the assigned parameter, the computer recognizes this and illuminates the MIL. Often, the computer is also programmed to switch into "failure mode," employing a pre-mapped strategy to compensate for the failure. It may also to create a noticeable driveability symptom, so if the MIL is not enough motivation, the driver will be more inclined to take the vehicle in for service.

So, here we are at the crux (and bucks) of the matter. There's no question that when there's a driveability symptom along with a lit MIL, your vehicle should be taken to a mechanic. What if there is no driveability symptom? Engine management/emission control systems are so sensitive that the MIL will light up due to driver-induced stimuli. These might include leaving the fuel filler cap loose, driving the vehicle too hard under extreme conditions (blasting across the desert during summer with the air conditioning on max and a small trailer in tow), or using the wrong grade of fuel.

Obviously you could correct these problems yourself without a trip to a pro, and often, after several drive cycles, the MIL may reset itself. Generally speaking, manufacturers' warranties do not cover such causes, and the vehicle's owner would have to foot the bill for a diagnosis and reset of the computer. While some information doesn't come cheaply, many motorists may feel that the "better safe than sorry" adage applies here, and it's hard to argue with that. It may help to think of those MILs as good motivation to pay better attention to how you interact with your vehicle. And they sure beat the old days of idiot lights.

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • The nearest Volvo dealer is 160 miles away. Best $15 bucks I have spent in a long time! Paul M Corpus Christi, TX
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
  • http://ww2.justanswer.com/uploads/TE/TedG/2012-6-15_14759_avaLarge.64x64.jpg Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    1596
    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    1311
    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    ASE Master Tech

    Satisfied Customers:

    2367
    ASE Master Tech advanced level specialist
  • http://ww2.justanswer.com/uploads/SU/supermechanic/2013-8-23_03546_500.64x64.jpg Jerry's Avatar

    Jerry

    Master Mechanic

    Satisfied Customers:

    1906
    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    942
    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
  • http://ww2.justanswer.com/uploads/ST/Steve7654/2012-6-5_215929_japic800x660.64x64.jpg Steve's Avatar

    Steve

    Auto Service Technician

    Satisfied Customers:

    1980
    25+ yrs experience as a professional working technician; ASE L1 master technician