Check Engine Code Question

[raybo]

Have a 99 Subaru Legacy wagon. Check Engine light is on. So I went to Auto Zone where they will read the diagnotic code for free. The code was read as P1133 with the message "Fuel Air Mixture". (Im assuming they knew how to do it right)

 

Previously the check engine light has occasionally gone on when the gas tank got down to 3/4 full but I could get the light to go off by disconnecting the battery for a minute but now that doesnt work.

 

Any thoughts????????

[Legacy777]

Not sure what exactly that code means, but it sounds like there may be an issue with the coolant temp sensor, or possibly O2 sensor....and that's causing the air fuel mixture to be out of whack. Other possibility is the ECU might be acting weird.

[SuBrat84]

MAF or MAP or whatever? just a thought

[UMT]

Not sure what exactly that code means, but it sounds like there may be an issue with the coolant temp sensor, or possibly O2 sensor....and that's causing the air fuel mixture to be out of whack. Other possibility is the ECU might be acting weird.

 

 

Nah, if you don't tighten the gas cap up,,, it will turn the check engine light on. I know my cap was getting bad anyway as I had it over to AutoZone with similiar problem last week.

 

I'm really more curious to know how to reset the 'check engine' light...

 

Thanks,

 

UMT

[Adnan]

I'm really more curious to know how to reset the 'check engine' light...

 

Thanks,

 

UMT

 

Hi,

 

The same code scanner that reads out the code allows you to clear any set codes.

 

Regards,

Adnan

[Adam N.D.J.]

Px1xx series code can be the fault of an O2 sensor. The front (or pre-cat) O2 controls the mixture, and one that is lazy, or not working properly, but withing "specs" will usually set one of these.

 

On the gas cap off problem, that will set a P04xx code, or EVAP system malfunction/leak

 

Having someone pull a code for your at an autoparts store (i.e. Autozone) is perfectly fine, especially if it is an OBDII system (96 and newer), as the OBDII system regulations state that all the diagnostic codes have to be within a certain area they are layed out like this.

Codes are set up with a 5 digit identifier, the first digit is a letter.

B-body, P-powertrain, C-Chassis, U-Network

The second digit will be a 0 or 1, 0 is an SAE or universal, and a 1 is a manufacturer specific.

The next (3rd) digit will be a 1-8 and this breaks down the problem to a specific area.

x1xx codes are fuel/air, x2xx codes are injections controls, x3xx codes are ignition system/misfire x4xx codes are aux emissions controls, x5xx codes are vehicle speed and idle control, x6xx codes are computer output circuits, x7xx and x8xx are transmission systems

And finally the last 2 digits will be the actual code it's self, and can be 00-99 depending on the codes it's self.

[ron2368]

I went for inspection and the CEL was on . Mechanic said it was the antiknock so he replaced it for 150$. The CEL came back on 4 days later when I filled the gas tank. He wants to read the codes again but should I allow any repairs? Is it possible to keep getting codes for related problems and never really fixing it?

[Adam N.D.J.]

Sometimes one problem will actually spawn another problem, that coupled with a lot of mechanics will pull a code, then just change out the part mentioned in the code, without any other diagnostic.

I actually had a car that came in with a knock sensor code, checked the sensor it's self, and it was working just fine, within specs and everything. Although when it was running I noticed that it was all over the place. Turned out that it had a bad rod bearing, that wasn't loud enough for me to pick up by ear, but the KS was picking it, and pulling timing. If I had just changed out the sensor, then it would have just thrown the code again.

Another time I found an air/fuel mix code, instead of it being a problem with the motor or any of the sensors, it was actually the fuel in the car. It had sat out in a field for a couple years and was bad. Pulled all the fuel out, replaced the filters and filled it with new, and now it runs tops, without any codes.

So in short, sometimes the onboard diagnostics are good, sometimes not so. Depending on your mechanic, it can actually be a double edged sword. Might worth while to take it somewhere where you can get the codes pulled for free, then if it is the same problem, then go talk to the mech.

[Steve530]

Have a 99 Subaru Legacy wagon. Check Engine light is on. So I went to Auto Zone where they will read the diagnotic code for free. The code was read as P1133 with the message "Fuel Air Mixture". (Im assuming they knew how to do it right)

 

Previously the check engine light has occasionally gone on when the gas tank got down to 3/4 full but I could get the light to go off by disconnecting the battery for a minute but now that doesnt work.

 

Any thoughts????????

 

A quick search turned up this webpage http://www.troublecodes.net/Subaru/.

 

I have no idea if it is correct, but there is not a P1133 code listed for Subaru. But the codes around it indicate a failure of the O2 sensor in front of the catalytic convertor. As someone mentioned, this is the sensor that the ECU uses to control the fuel mixture.

 

So my guess is that the front O2 sensor is bad.