PDA

View Full Version : Check Engine Codes twice?



rccolacc
01-06-2006, 12:23 AM
I checked my check engine codes tonight. I got a code 21 twice (it flashed 21 up consecutively). I know this is the O2 sensor code, but why would it flash twice?
I replaced the upstream O2 sensor a year ago (about 12K miles). Is it possible for it to be going bad again? The dealer says other things will throw the O2 sensor code--- such as a bad coolant sensor making the engine run rich. I don't want to replace that O2 sensor just to have it go out again. I think it was $70--- not something I want to spend every few months.
Thanks for your help.
-RC

fredr1980
01-06-2006, 02:30 PM
If you have the 4.0L you have 2 Oxygen sensors, one right behind the exhaust manifold and one right behind the catalytic converter. I had the check engine light come on about 2 months ago for the CAT and I had just replaced one of the sensors. I just replaced the other and the light went away. Hope this helps.

Fred R.

CurtP
01-06-2006, 03:33 PM
Flashing codes on the dash only gives you a partial idea what the problem is. If it's OBDII (96+), then it would be a good investment to buy a code scanner that plugs into the ALDL connector under the dash - it will give you a lot more details about the problem.

You're probably getting flashed 21 twice because there is more than one code stored for that general system.

rccolacc
01-06-2006, 03:42 PM
Yeah, my ZJ is a '97. Where do you get these code scanners? Is it a dealer item?
Thanks for the help.
-RC

CurtP
01-06-2006, 03:52 PM
Most automotive parts stores carry them. I was at Sears a week before Christmas and saw a Akron scanner with digital display for OBDII for less than $100. A quick Google came up with the Actron CP9125 OBDII PocketScan for $70 from Levine Auto & Truck (http://www.levineautoparts.com/acpoobdiicor.html).

I'm using a AutoXray EZ-Read 2000 OBDI/II code scanner. I think it was around $180 (but it comes with several OBDI cables and a standard OBDII cable).