What all do service centers check when doing a diagnostics check?

Question

I had one done on my vehicle today and they gave me a lot of information. I'm still a little worried though. The reason I got the diagnostics test ran on it was because my engine light was coming on when my car got warmed up. I was told by the service dept that this is probably due to a bad sensor. My car does not overheat, no white smoke, temperature gauges are all good, but my oil looks really dark and when the dipstick has been wiped on a cloth, the color looks kind of light black or dark greyish. If it was something serious like a blown gasket or cracked head, would they have told me after doing the diagnostics test? Is this something I should be concerned about, or is it just dirty oil that needs changed?

Answer 1

they check your muffler bearings, your timing light, your exhaust intake transfer case, your motor mount pressure, your blinker fluid and most importantly your ID10T lights. check the PU.55Y manual for more information.
but for real, if you've got more than 3K miles on your car since your last oil change, then change it ( no better way to make your car last than to keep up with the oil changes).

Answer 2

Did the mechanic tell you whether the oxygen sensor was okay? Is that the sensor he mentioned? That can make your engine light go on. If so, you'll mostly likely see a drop in fuel economy.

Also, when you had it checked, did he tell you which code caused the light to come on? I would think if the code for the oxygen sensor came up...he would have known for sure that it was the sensor and not just said "probably".

One other popular reason for an engine light to go on, believe it or not, is that the gas cap is not put on tightly, make sure your gas cap is clean and on tight (until it clicks). Also on newer cars, just by keeping the car running while getting gas can cause the engine light to come on.

Lastly, is it the Check Engine Light or Service Engine Soon light that is coming on? If it's actually the Service Engine Soon light that's coming on, that would mean that the computer senses that it's time to change the oil. Sounds like you do need an oil change anyway.

I suggest checking your gas cap and getting an oil change. Also, always shut your ignition off when getting gas. Then, if your check engine light comes on again try to take it to a local AutoZone while it's still on. Most areas have one. They sell car parts. You can go to an AutoZone and have it scanned at no cost and they will tell you the codes and give you repair suggestions and sometimes even an idea about repair costs.


Good luck to you!

Answer 3

The service center should have been able to tell you what the light came on for. What they do when there is an engine light problem is hook it up to a scan tool. The scan tool shows the computer inputs,outputs, and code messages. The light comes on when a code is trggered(just on a guess your code sounds like an oxygen sensor type thing). They would only check where the concern was mentioned so they wouldn't have checked the oil. You should get the oil changed since it sounds due for it. Maybe just goto an auto parts store and ask to have a code read. They do it for free and may give you an actual answer rather that what you were told at the service center.

Answer 4

You wouldnt be able to detect a cracked head with a simple diagnostic test. It would require the use of florescent (sp?) dye, and your check engine light wouldnt be on if you had a cracked head.
If your car is an 86-96 (i think that is the obd1 (on board diagnostics 1) years) you can pull the codes yourself with a paperclip. But not knowing what kind of car you have kinda limits the answers or advice i can give you. But yeah, most of the time the check engine light will come on because of a faulty sensor.

Answer 5

Dirty oil needing a changing. I wokr in a garage and I have worked in lube shops before. Its dirty oil, I would take it back to the shop and have further diagnosis done if they didn't narrow down waht sensor and have them do an oil change.