Jeeps Canada - Jeep Forums - P0303 and Coolant

On Sun, 26 Nov 2006 13:22:38 -0800, Outatime <WhoKnows@here.com>
wrote:

>There is a big difference between a code SCANNER and a code READER.
>
>The $79 cheapies you see at Pep Boys are readers. If all you want to do
>is retrieve numeric codes and reset the MIL, this is fine.
>
>For another $100-150 more, a code SCANNER will give you information
>about idle speed, IAT temp, real-time TPS voltage, O2 voltate readings,
>fuel trim percentages (long and short term), exact coolant temp at the
>sensor, RPM variations, cylinder power balances, and my favorite: the
>ever-popular rediness check, which tests every input/output sensor to
>make sure everything is in-spec before visting the smog-check testing
>center.

The readiness check doesn't test any sensors. It only shows you
whether the non continuous monitors have run.

>
>You can spend more if you need transmission diagnostics and other
>esoteric information. I don't need all of that stuff, but the O2 sensor
>data is valuable to me: I can look at each sensor's performance and tell
>if there's a pending problem, or if one has failed, know EXACTLY which
>one at a glance without having to look anything up in a manual.
>
>I settled on an Actron 9145 code scanner for about $180 on sale. This
>is more than most shadetree mechanics will ever need. I've easily
>recouped that cost in the last few years by reading my own codes,
>resetting the 'crank sensor out of spec' when I unplug it to prime the
>engine after an oil/filter change, and the one infamous time when I
>removed/cleaned the EGR valve and had a serious out-of-spec idle problem
>afterwards. (It actually said the EGR valve gasket was leaking - how
>the computer knew that is a mystery to me.)
>
>Either way, a code scanner/reader is a very good investment.
>
>Incidentally, if all you want is codes, newer Chrysler and Jeep products
>will display this on the odometer display by pressing the odometer reset
>button while turning the key to the RUN position --no need to buy a
>seperate code reader if this will suffice.