Engine and hold lights flashing

[HeavyDuty]

Well if someone at a dealership did as you suggested I would never take my car to them...ever. The reason you pay high labor charges at a dealership in part is for EXPERIANCE and also in part for EQUIPMENT to test. Any one can throw parts at a problem in hopes of fixing it....but I would not call them a mechanic LOL

The person you want to be working on your car mechanic or not dealership or not is the guy you call up and say hey every time I start my Aveo it sets a P300 and he say's oh that's the X and you take it there and he puts X in and away you go problem fixed. This only comes from experience and logic.

Every single part can be tested in the hands of someone a) with the knowledge and b) the tool to test it...and last but not least even with previous two they still need to have some LOGIC.

These days that's VERY hard to find I am afraid, rapid changes in technology and a number of other factors play into this as well.

You are having a P300 code set ?

In my 2009 Chev Aveo owners manual there is a paragraph about the transmission not shifting does the 2005 manual have the same blurp ? A random miss fire could be caused by the WRONG plugs......or even a fuel injector, the driver can narrow it right down, if he has some mechanical knowledge....the little test drive mechanics "USE' to do was for this reason.

It seems in at least one of these cases the car is running fine but setting a code, if it tells you it has a misfire and there's no misfire....then whatever detects misfires is the problem...if a misfire is present and setting a code, well that's another ball of wax.

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.

Does the throttlebody have anything to do with engine speed or possible engine speed fluctuations ? Indeed it does is that your problem, I can't say but am sure your TB could use cleaning anyways right (that's some logic).

If the mechanic told you the relearn wasn't the problem...take it somewhere else and have it done. Mechanics have this really bad habit of you can't possibly know anything....and may have dismissed it just because you suggested it and further they may not even know how to do it so of course THAT CANT BE THE PROBLEM.

[ak1you]

Here is something I really can't understand at all. Apparently modern cars are so tough that if a professional mechanic can't get a diagnostic handed to them from a machine, they just throw up their hands and say "duh, never seen that before" (which is same thing I would usually say). Ok, fine - it is what it is; but why can't they at least round up the usual suspects? Yes, we know that there are lots of possibilities for the P0300, but some of them are fairly well-known, and should be easy and simple for a Stealership to try (sorry about the profanity Vanessa). It's the same thing that we do, only they don't need to buy the parts. Why does an Aveo dealer not have one set of good plugs, wires, coil, cam sensor (and maybe some other easy ones I'm not thinking of) on hand, ready to try as temps. How long is it going to take a pro to swap those things out? First ask the customer if they want to pay for a part-sway try (labor only). Then, if something works, take out the temp and install a new one off the shelf - case solved. If nothing works, bill the customer for the time to install/remove the parts.
Ok, that's the end of my useless rant. Personally, I would first try a new set of OEM plugs (regardless of how new the existing ones are). Then, maybe go to a boneyard and pick up a basketfull of parts like the ones above. Might as well try hanging parts if the shop can't figure it out

GUESS WHAT...... I did it well you are going to need a Crankshaft relearn procedure. However I had better luck at a Goodyear/Conrad tire shop then at the dealer. They were able to do it rather quickly, But right before I went their I had the crankshaft sensor replaced so one of them worked or a combination. I am just happy I don't have to deal with my wife nagging about it.

[ak1you]

GUESS WHAT...... I did it well you are going to need a Crankshaft relearn procedure. However I had better luck at a Goodyear/Conrad tire shop then at the dealer. They were able to do it rather quickly, But right before I went their I had the crankshaft sensor replaced so one of them worked or a combination. I am just happy I don't have to deal with my wife nagging about it.

[ak1you]

Oh and the car is shifting perfectly now.

[avguy]

ak1you,
Thanks for posting the result. I think you're saying that Goodyear replaced the crank sensor, and a bunch of other things as well, and that the combination of parts fixed the problem. Is that correct? If so, did they put a parts list on your bill?

[ak1you]

ak1you,
Thanks for posting the result. I think you're saying that Goodyear replaced the crank sensor, and a bunch of other things as well, and that the combination of parts fixed the problem. Is that correct? If so, did they put a parts list on your bill?

first I took it to the dealer tried the procedure 3 times no luck. After that I changed the sensor and took to goodyear.Now it's all good.

[ak1you]

first I took it to the dealer tried the procedure 3 times no luck. After that I changed the sensor and took to goodyear.They didn't change anythings. Now it's all good.

[xyz]

Hi all I have a similar problem, Aveo 2005 in limp mode with high gas mileage after engine replacement because of idler pulley failure.
When replacing the engine I noticed the transmission coolant line had failed in the rad, so i flushed the coolant out of the tranny and replaced the rad
Seems a huge coincidence the idler pulley and the rad went at the same time or would one cause the other to fail ?
The code is p0300 random multiple cylinder misfire.
I have been driving it in limp mode over a month and on two occasions it came out of limp mode but still had the cel on, once for over an hour (drove nice shifting properly) and the other time for arround 5 mins on both occasions i was checking wires under the hood just prior,but can not replicate.
I have checked the harness voltages and all correct, changed the cps map tps plugs and leads misted the coils looked OK.
I had no ideas left so i took it to the stealership for a cam position sensor relearn.
They said it was a slipped timing belt and the relearn would not take, so i checked the belt and it was correct.
I am now thinking it may need the ecm reflashing.
Any ideas or suggestions would be appreciated

[avguy]

... and on two occasions it came out of limp mode but still had the cel on, once for over an hour (drove nice shifting properly) and the other time for arround 5 mins on both occasions i was checking wires under the hood just prior,but can not replicate ....

.... I had no ideas left so i took it to the stealership for a cam position sensor relearn.
They said it was a slipped timing belt and the relearn would not take, so i checked the belt and it was correct ......

Sounds like you fiddled with the wires first, and then it drove fine? If so, IMO that's a smoking gun pointing to some type of electrical issue, such as a cut/broken wire. Could of course also be a bad connector to some part such as the coils, or maybe even a part (coil, etc.) that "reconnects" internally for a short time after stuff was moved around. Maybe a multi-meter test on various points in the system might reveal the problem.

Did you suggest that the stealership "relearn" the tech who told you the timing belt had slipped?

[xyz]

"relearn" the tech who told you the timing belt had slipped?

Good one,

I went through every connector i could find, today (again), sprayed them all with contact cleaner, checked voltages and signal wires all are correct. I also did a dry compression test and all cylinders are within 10 psi (so not the valves or rings). I am thinking to try a different stealership (Courtesy Chevrolet in Toronto don't seem to know how to do a relearn) Hopefully the next one has techs that know how to do the relearn.
Anyone got a Toronto recommendation.