2008 Mazda5 CEL came and went a couple of times. No symptoms so far...

[coolmazda5]

2008 Mazda5, ~50k mi. A couple of days ago I had to drive through extremely heavy rain for a few hours and the next day the CEL came on. It stayed on and off until I put gas. No weird engine symptoms (loss of power, lurching, fuel economy changes) and no fluids problems, all checks allright. Fuel cap is tightened as usual.

Any ideas what it could be (or have been)? Humidity fooling a sensor or something? The reader won't through a code unless the light comes back I believe

Thanks

 

[kw_da]

The code should still be set, it may erase automatically after a certain time. Doesn't hurt to check if it is still there.

 

[Secondtyme]

Keep an eye on your temp gauge if the CEL recurs. When the light comes on look at the temp and see if it has gone from center of the gauge to near the bottom all of a sudden. This is a good indicator of the dreaded 1026 erratic thermostat CEL. Do you have a code reader? Your initial post makes it seem as though you do...

 

[Donewood]

Usually related to pollution control. So fuel air mixture, oxygen sensor, ignition map, Evap sys (if you fill the tube, as in top off the fuel tank while pulling the nozzle part way out,) and such. Some codes will automatically switch the ignition to a "Limp home mode" which usually means the car drives great but it will run slightly rich decreasing gas mileage by a bit.

Get yourself a cheap OBDII reader and software for your computer, cheaper than having the stealership scoop once!! Than you can self diagnose, and reset a the ECL yourself. Most programs give you all kinds of abilities the dealership doesn't want you to have. Change mileage, language settings and the like.

 

[sac02]

Recent codes are often stored even when they aren't displayed.

$20 bluetooth OBDII adapter + $5 Torque app.
Makes you look like a wizard to your friends when they mention a CELs on their car - you reach in your glove box for the adapter, reach in your pocket for your phone, and 30sec later tell them what's up with their car. Plus you are holding the Internet in your hand as you pull codes, so Googling is easy.

 

[coolmazda5]

Thanks all for the responses, it came and went this morning again, and code P0138 it is:

P0138 Rear HO2S circuit high input ON 2 CCM.


I'm thinking is about to go. Now to try to get the part on the cheap. Good thing it just passed the inspection


http://www.mazdas247.com/forum/showthread.php?123662124-Mazda-2-3L-CEL-Codes

http://www.mazdas247.com/forum/showthread.php?123791598-O2-Sensor-(P0138)-CEL-Code

http://www.mazdas247.com/forum/showthread.php?123804150-CEL-P0138-Rear-O2-Sensor

 

[rodslinger]

I have a rear O2 I bought for testing when I was getting a catalyst efficiency code. Probably has 500 miles on it. Paypal me $20 and I'll send it via USPS.

 

[coolmazda5]

I have a rear O2 I bought for testing when I was getting a catalyst efficiency code. Probably has 500 miles on it. Paypal me $20 and I'll send it via USPS.

Thanks for the offer rodslinger. Well, no more rain, weather has been much better and the CEL has not come back since. Also, by doing more research it seems that the code is thrown more often than I thought on different brands after heavy rain, under carriage car washes or even puddles, I hope it is the same case, if not be sure I'll be PM'ing you

 

[Silentnoise713]

Sure sounds like the rear o2 is on its way out, same as how I experienced it. I'd suggest you scoop up that offer from Rod. You don't know if a passer-by (there seem to be a lot of those) might PM him before you.