Check Engine Light

I've had a service engine soon light come on because of a dirty air filter before.

 

I've never seen that happen in the 15 years I've been in the car business, but I guess it's possible in one of two ways -

- contaminating the mass air flow sensor and causing erratic readings
- starving the engine for air and causing a false rich condition forcing the fuel trims to max out in the negatives

To the op, take your car to autozone and get them to pull the code(s) then tell me what they are and what you are driving, I'll tell you the possibilities and how to fix it.

The code itself does not tell you what's wrong. All it does is narrow it down to a subsystem. For example an oxygen sensor code could be a bad oxygen sensor, bad wiring, bad computer, exhaust leak, etc.

An evap code could be the fuel cap seal bad/loose, but it could also be a million other things. Especially if it's a Toyota or GM car. Evaporative emissions systems are complicated. Speculation of what the code could be is a waste of time when auto parts stores will pull the codes for free. Then they will try to sell you whatever the code points to - don't buy it.

If you are having no driveability issues there is a good chance it's an oxygen heater circuit code or an evap code, but once again speculation is a waste of time.

 

Auto parts stores will do that? Is it free?

 

They will here. Shit, you can get an OBD2 code reader for like $40.

It won't talk to any other modules (computers) other than than the engine control module, and you won't be able to view or graph live data but it will talk over generic SAE protocols and give you 'P' codes. For example a random misfire P0300, cylinder 1 misfire P0301, catalyst efficiency P0420, etc.

And it will give you the ability to clear the engine codes. But keep in mind for smog testing, they look at the monitors. If all the monitors haven't run then they know someone just cleared codes. Or at least any technician who knows his ass from a hole in the ground does.

 

There you go, $18 for an Autel code reader. They make good products. I have one of their full function $5,000 scan tools and love it.

http://www.amazon.com/Autel-MaxiScan-MS300-Diagnostic-Vehicles/dp/B001LHVOVK/ref=sr_1_1?ie=UTF8&qid=1386035724&sr=8-1&keywords=obd2+code+reader"]Amazon.com: Autel MaxiScan MS300 CAN Diagnostic Scan Tool for OBDII Vehicles: Automotive

 

yeah those autel are cheap...next one im getting is a cheapo autel with srs and abs...i want the one with scan functions though so i can see o2 info while its running

right now im stuck whenever an abs problem comes up ..it usually ends up being a bearing

 

I use a labscope for that.

But if you don't mind spending around $1200, seriously get the DS708. Full bidirectional controls. I just got the maxisys because I love the tablets, but honesly that maxidas (ds708) has damn near full coverage. I've coded VW and Land Rover modules with it, all the service bay tests, Merc service light resets, adaptions, relearns, Ford power balance.

And it has wifi and autoscan. Fucking INCREDIBLE tool for the price. I still use it over the Solus Ultra and the Maxisys all the time. It's a great go to scan tool.

 

$1293 with the TPMS tool. You seriously cannot beat that.

http://www.tooltopia.com/autel-ds708tpr.aspx

 

Thanks Dev that good to know,

Yeah I remember spending like $300 on labor just to get damn check engine like fixed.

 

Hey, we all have to eat :2thumbsup:

I've spent over $50k on tools and countless hours learning and busting my knuckles, as long as it gets fixed you are paying for the expertise.

 

Nope, my husband fixes my car when it breaks. You can't pass inspection in Texas with your check engine light on. Last time mine was on, I needed a new spark plug. You can normally go to O'Reilly's or Autozone and borrow their code reader while you're in the parking lot, doesn't cost a thing, and it'll give you a code you can easily Google.

 

Most common problem for an check engine light is the o2 sensor can be checked for free at a place like autozone

 

Lol. I give up

 

Don't worry the navy pollutes much more than a poorly running car.

 

Lol, the navy pollutes more than some poorly running countrys.

 

Since most people have smart phones nowadays, You can go on ebay and buy a cheap OBD II ELM327 blu tooth code reader. Download the torque app or one you like for free or pay, And find out 70% of the cars system.

I should have clarified in my first post as mentioned that a light and no change in operation means jack shit. Even more so saying 02 sensor, Which bank? Up or down stream? 1 or 2? etc.

Best bet is to get a cheap blu tooth ELM327 so you can narrow down the problem. You can also clear CEL lights and pending fault codes. Its cheap insurance in the long run and does about as much as a cheap code reader or more from your phone.

 

mine was coming on and turning back off randomly for a while there, but it's been off for a while now. of course, now that i posted this i'm sure it's about to come back on permanently.

my ABS and brake lights do the same thing, coming on randomly, and then turning off on their own. that's been going on for years, and no one has ever found anything significantly wrong with my brakes.

 

Sometimes the lights just come on.

 

Thats why I'd rather pay someone who knows what they're doing then waste time trying to fix it myself. The same thing happens in my field, clients pay me for what I know, not for what I do.

 

The check engine light is also known as malfunction indicator lamp (MIL). It shows when having a glitch in the electronic control module of vehicles. Commonly, the check engine light is positioned within the instrument console. In some older vehicles, the check engine light was referred to as "engine" or "trouble", which demonstrated small problems including overheating or flat oil pressure inside the motor. The check engine light is usually of golden or reddish color, and there are two types of it:

enduring check engine light - indicates minor situations
flashing check motor light - is triggered when there is a serious problem in the engine.

Source : http://checkenginecode.com/flashing_check_engine.html