check engine light

[skelly]

I have an 1997 Imprezza AT 2.2L EJ22 128K. The check engine light comes on sporadically. It seems related to a hot engine, but the temp. gauge is in the normal range. For the last 20K, it has been dealer serviced (Herb Gordon in MD)- and now the car is getting 5W30 synthetic oil rather than 10W30 oil. Lately I am also using 89 fuel, rather than the 87 fuel. Just wondering if there might be a relation to these two changes.

 

I have original thermostat. I think water pump was changed with timing belt at 90K. Dealer flushed radiator at 120K, and present antifreeze color not indicative of any problems - no oil residue - and all fluid levels on target. All fans working (dealer did safety check and would have noticed if they weren't). I do have a helicoil for one spark plug and I wonder if it is coming loose after 30K. (Since GrossGary is in my neighborhood, I asked him to recommend a machine shop to properly take care of threads.) Seems unrelated to speed. No obvious leaks that I can detect - will place flat cardboard box under car for a double check.

 

Right now to address problem I am doing idiot stuff, in part, because the timing belt was changed and the antifreeze does not indicate a problem, and in part because it is sporatic - idiot stuff like taking gas cap on/off (is it related to a full tank of gas?), putting hood up when at rest stop, and driving with heat on! which is a trial in these 90+ days (Maryland). Idiot stuff because I was able to drive my car on 3 cylinders when the spark plug originally blew (chose extra cleaning charge rather than tow charge). None of these actions seems associated with having it go off again.

 

Driving habits such that rpm no more than 3: currently 2 1/2 hrs (150miles) 2X on I95 weekends (traffic willing, up to 75); and 30 min (25 miles) 2X on normal commute day (no more than 45).

 

Any suggestions? Should I get a new radiator cap? Current cap looks/feels tight to me, and dealer probably would have noticed when flushed radiator anyway.

 

Will Auto Parts Store be able to read check engine light code if it has gone off? If so, for how long after?

 

Long Post, Thanks for any suggestions.

skelly

[PAezb]

Getting the codes would help narrow down the issue before speculating on the cause and throwing money on parts hoping to solve the problem. If you don't have or want to spend the money for OBDII scanner, some auto stores like AutoZone will/use to scan the codes for free. There often will be a code stored, most likely, even after the CEL has disappeared.

[skelly]

Getting the codes would help narrow down the issue...

 

Dealer performed "multipoint vehicle checkup inspection" on July 25 and diagnostic tests included engine management codes, transmission management codes, and ABS system codes. All checked out "OK". I know I had sporadic CEL so was surprised they were unable to detect a code history.

 

PS. Under-Car inspection (on lift) did not detect any leaks.

HVAC operation/leaks/hoses checked and OK

 

Dealer performed this inspection for free- I got lucky, I guess - but now I find myself second guessing them- and I am trying to locate a MD store that will read the codes-

Thanks

skelly Still

[Manarius]

The car doesn't need 89. 87 works just fine.

[nipper]

We need the codes. Most likely its an O2 sensor.

 

 

 

nipper

[Rooster2]

When Autozone pulled my codes on my OBW, I learned that the knock sensor was bad. It was an intermitten light that came on. AZ told me they could only pull the code to learn the problem, if and when the check engine light was on.

[nipper]

When Autozone pulled my codes on my OBW, I learned that the knock sensor was bad. It was an intermitten light that came on. AZ told me they could only pull the code to learn the problem, if and when the check engine light was on.

 

This is true, but you can also rent the code reader to have it for whne this happens.

 

Alos look at the knock sensor, if it is cracked or loose it needs to be replaced.

 

nipper

[skelly]

Need codes. Most likely its an O2 sensor....

 

Hi -

Yes- will codes, but thought dealer already read them, so went ahead with long post ... with big question related to how soon codes must be read since is sporatic problem.

 

After reading all the posts it does seem as if it's the O2 sensor (and most likely front), despite the fact that I'm getting terrific gas mileage. I am getting close to 28 mph highway (rarely use AC through lifetime of car). Is condition of O2 sensor something that can assess via an under-car inspection? Something the Multipoint checkup inspection missed? What additional problems am I inviting by driving a car with a bad O2 sensor?

 

Anyway, for those who do all their own work, here's some satisfaction:

Brought my car in for an oil change, and left after paying $420.00! The right front axel boot was torn, and they replaced the front axle shaft with a reconditioned one. Parts 225.00 Labor 180.00. HA!

 

skelly

[86BRATMAN]

You can't tell an o2 problem with a visual inspection. Unless its got a broken wire, but the cel would most likely be constant if that were the case.

 

You can run it with a bad o2 with no bad problems other than suffering fuel economy.

 

If the dealer read the memory they should be able to tell you what the code was for.

[zstalker]

seriously...need the code. the code will be stored in the computer's memory for a decent amount of time after the light turns off. if the "check engine" light comes on, there is a code, and it is a terrible idea trying to diagnose unknown problems based on information not related to your car (info fron the forum) without knowing the code that turned the light on. I'd hate to see you replace O2 sensors, thermostat, whatever, and find the code was for your gas-cap being loose...y'know? When the light comes on next time, stop by a local parts store (checker, advance auto, napa, car quest, autozone, whatever is nearest) and get the code pulled. it will be a Pxxxx code, with numbers for the x's, like P0456 or P0133 or P1844 (just random ones...for examples). without that, proceding is futile.

~Erik~

[eryque]

Lots of parts stores will read the codes for free. If you'd rather have the tool to do it yourself they're not that expensive. I picked one up at Harbor Freight for $40.

[PAezb]

Lots of parts stores will read the codes for free. If you'd rather have the tool to do it yourself they're not that expensive. I picked one up at Harbor Freight for $40.

 

I was looking at these: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94169

 

If I may ask, what's you assessment on it's quality?

 

 

8/8/07

Thought I'd drop this link in here too, another Cen-Tech ODB-II code reader that supports text display and a few others not in the smaller unit. Cheapest price I've seen for any text capable reader:

 

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94217

[eryque]

It works. I don't know what else to say about it. For $40 I can't ask for much more. It doesn't do anything fancy, just check codes which you have to look up in the included reference booklet. It's not built like a Fluke meter or anything. Drop it too many times and you'll probably crack the circuit board. So don't drop it.

 

Was it worth it? Saturday night I was trying to figure out what the heck I'd done to cause the howling noise in my engine, which I eventually traced to the idle air control valve. It was after dark when I buttoned it up. Got in the car a bit later to get the groceries and got a CEL immediately when I started up. I plugged in the reader and a minute later found that there was a low voltage condition in the MAF circuit. WTF???? says I. Oh yeah, I forgot the electrical connector.

 

Three minutes from start engine to fix. In the dark. It was after 10 and the parts store was closed so I couldn't go to them for help.

 

Was it worth the $40? Damn right.

[skelly]

Here is the Code for my sporadic CEL (thanks to AutoZone):

P0122

Says TP (Throttle Position) sensor

Probable causes

1 - sensor open or shorted internally - replace component

2- Check connector and wiring to sensor

 

The PCM has determined that the input from the throttle position sensor is lower than expected for the current engine operating conditions.

 

NOTE- CEL not on at the time, and is 90 + here! (Also, Dealer did not use an OBDII)

 

NOW what? (As a newbi- suspect #2). What additional symptoms, other than CEL, should I have noticed? Did I risk further damage to car while driving with CEL on?

Thanks

skelly

[nipper]

No you didnt hurt anything. When you get a steady flashing CEL then you need to get it checked asap.

 

FIrst thing to do is disconnect the TPS sensor then reconnect it. If the contacts are dirty, just that is enough to clean them.

 

TPS are not a common code to come up, so I would have faith in that code. What it is saying That at X conditions the ecu should be getting Y input from the TPS. It is not seeing it all the time, so its giving a code.

Single codes are fairly straight forward.

 

Have them clear the code, do the unplug trick, and wait. If the CEL comes back have them scan it again.

 

Since there is no driveability issue right now we can take our time.

 

nipper