Paging TSTONE! Car stuff!! (inspection, codes, shop)

[catfancier]

Hey TStone, my (and all city-data's) automotive guru....

So in the latest installment of our "Check Engine Light" drama...you may recall that in late August I had this issue and wound up going to Christian Brothers and becoming the proud new owner of an oxygen sensor. (And $300 lighter in the wallet.)

So...fast forward to early last week: Check Engine Light, The Sequel.

Light comes on, Catfancier freaks. (I have a 2002 Toyota Highlander, so I know a six-nearly-seven-year-old car is going to have issues.) I run errands and such and probably turn the car on/off about four times. Light stays on. So Thursday morning I call Christian Bros and say I'm heading over.

Get to their place, park and turn off car. About 40 min. later when mechanic gets to my car -- Check Engine Light has disappeared! All diagnostics are fine; he can't find any problems. He asks if the light was on when I started car that day -- of course I say yes. He says sometimes it takes "three or four cycles" for the car's computer to, in essence, realize it had a false alarm. So I get my oil/filter changed while I'm there and happily head home.

Until Friday noonish...about two miles into my first drive of the day (clue? engine warmed up??) the Check Engine Light comes back on!! Been on since, after at least 5 or 6 car starts.

So I plan to call Christian Bros first thing Monday a.m. and say I'm headin' back...if it's the sensor they replaced there is a warranty. The thing is, I plan a 60-mile drive Tues and am quite anxious about not having car trouble away from home, even though I am a TX AAA member....

So...long explanatory intro aside...Tstone (and anyone else, of course) ...any thoughts or advice?? A relative who's also in the biz says when I go back, to KEEP THE ENGINE RUNNING so they can do the diagnostics while the light is on. (In other words, don't park and turn the car off.) Think that makes sense? (Other than wasting gas if they can't get to it immediately....)

I feel about cars the way I do about computers...I don't care HOW they work -- I just want them to WORK!!!!

Mucho thankso, CF

[Poltracker]

Not having your gas cap on tight can cause the check engine light to come on. Having said that, it is not completely needed for it to be on while the car is diagnosed. The code should be stored in the car's computer if you have not travelled with it off for more than about 70 miles. Alot of times the code will read O2 sensor but what you really need to find out is what is causing the o2 sensor to foul out and fix that. When was the last time you changed your plugs and wires? If the car misses, it could kick the sensor on, so many other things can too.

[Wysiwyg]

yup the code should be stored in there. have it read. at that age you can get typical codes like a slight slippage of the tranny(this goes on and off in my experience), lean fuel mix due to vacuum leaks, intermittent malfunction with sensors (camshaft position, throttle position etc). have the code read for free at Autozone or Advanced autoparts. Its also a good idea to own a code reader

[starkeshia]

Originally Posted by catfancier

The thing is, I plan a 60-mile drive Tues and am quite anxious about not having car trouble away from home, even though I am a TX AAA member....

You'll likely be fine. The most serious codes will cause a marked decrease in drivability.

A relative who's also in the biz says when I go back, to KEEP THE ENGINE RUNNING so they can do the diagnostics while the light is on. (In other words, don't park and turn the car off.) Think that makes sense?

No. It should preserve the code through multiple on/off cycles.

[tstone]

What's said is true. The check engine light throws a code into memory. When the light turns off, the code is still in memory. It doesn't go anywhere unless the computer is reset (PCM fuse is pulled, battery is disconnected, machine resets it, etc). If the shop has the proper diag tool, it should be able to retrieve the code even if the light turned off.

Ditto on what's said about Auto Zone. Get it checked free. Don't pay the diagnosis (rip).

Now the question is, what code is in the memory now?

When a car came into the shop & failed inspection with code P0442, it was almost always a loose gas cap.

[catfancier]

Ok, it would have helped if I could have found my receipt before I posted...the info is on it.

The computer stored code they got was P0161 02 heater circuit...but specs were all ok when the mechanic checked.

I am heading in shortly again so we shall see....

[tstone]

OBD-II Trouble Code: P0161 Oxygen O2 Sensor Circuit Low Voltage (Bank2, Sensor2)

Oxygen sensor again. Is it the same sensor giving you trouble? (If you have a V6 you should have a total of 4 sensors .)

There might be additional information stored in the computer that only the dealer can read with their Toyota-brand scanner. If you're chasing your tail on this one, it sounds like that kind of diagnosis is in order.

[catfancier]

Hi Tstone -

No it's not a V6...it's the base model 4-cylinder, 2WD.

I don't know if it's the Bank 2 Sensor 2 they replaced in august but they know I know if it is that one again this should be a warranty fix.

Will let you know! Thanks for the heads'up on going to a Toyota dealer if this happens again -- just none real close by.

[catfancier]

So OF COURSE the culprit is one of the OTHER 'rear' oxygen sensors...not the one they replaced in August. So another $325 to get rid of the "check engine light".... I kept the car running and the code showed up and indeed there was a "short" or whatever found in it.

arrrgghhh.

Thanks for all input though. I hope to start no more threads on this topic!!!