My PT Cruiser is playing the check engine light game but I do believe I have a short in the cooling system because I get air conditioning on the regular fan if the temperature gauge is all the way on the blue. In the Cruiser its the fan that is supposed to designate air conditioning or just plain air.

if it were just the light, I'd ignore it, but it's the engine performance. It's running ragged, and the engine is (sometimes) sputtering or hesitating. Gets my heart in my throat, I tell ya. The manual just says that continued driving with the CE light on may damage the emissions system.

sorry, monster & tw if I'm a car idiot. Actually, it's more of a tool/handy person idiot, but I've found after painful experience (and experimenting) in my life that such things are better left to people more adept with manual skills than me. I know my strengths, and that ain't one of them.

Which is why some people also much carry many green 2.75 by 6 inch sheets of paper in their wallet. Go somewhere and ask them to open the radiator. You observe what is inside and then ask the 'assistant' what he sees. The put the cap back on. Do not do anything else (but give him sheets of green paper). Then post here what was observed. Solutions are that simple - step by step.

It is required in most states.. If an errror code exists, then the car fails inspection.

At this point she's committed, to the tune of $800, and they didn't fix the problem. She has to go back to them and make them fix it, or get her money back and go elsewhere.

Plenty of options exist. When we choose not to learn basics, then compensate by moving plenty of green paper through wallets. It creates jobs. That's what paper is for. Compensates for not wanting to learn and compensates for labor. And so the term 'just compensation'.

Bottom line: simplest solution if one cannot check fluids in the radiator. Replace the Idle Air Control Valve. Just pay the money. DTC implies it is getting stuck as engine temperature changes. It does not necessarily explain the failure. But then other critical details (not provided) would probably define that or some other problem. Those details will not be forthcoming. So just replace the Idle Air Control Valve.

Only better techs would put an oscilloscope on the IACV wire. Then that problem could be observed. Most techs do not have sufficient knowledge and tools. And would be further stifled by insufficient details. What will they do? Replace the IACV - the shotgun solution.

Bottom line - that $800 spent on a new computer is gone. No way to recover that money - unless the dealer has a special place in his heart for Cloud. Move on. Replace the IAC valve (which was always my #1 suspect (considering almost no facts). A new valve has about a 65% chance of success - clearly the best option at this point. More money is the only remaining solution.

Bullshit, they took her money to fix the problem, and didn't. They owe her $800 dollars worth of fixing.

I'm sure they'd be willing to refund me the $500 + for the actual part . . . if they removed it and put my old PCM in there (if they even still have it). Don't really want that, though, nor do I want to make a big scene. I received the same diagnosis and suggest for a fix from two different places, and went with that, but I knew there was a chance that it wouldn't fix the problem. I will keep trying--have to, anyway, since it's my only transportation option.

I really appreciate everyone's advice. The Cellar is really great for that! I refuse to be ashamed that I'm not good at fixing cars. I'm not an idiot, but I'm not handy, either. I try to keep my car well-maintained anyway.

In the end, I listen to advice and use my own common sense.

They simply followed a simplistic diagnostic chart. It says if the valve clicks when voltage is applied, then replace the computer.

Well, an idle air control valve actually opens and closes quickly per commands from the computer. So quickly as to need an oscilloscope to actually see it. Computer monitors how fast the valve is responding. If the response is not what was ordered, then the computer flags a check engine code. If the valve works normally but too slow, then computer gets replaced (if only following the diagnostic chart). Valve can be sticky, partially clogged, etc. and still pass the on-off test.

The entire circuit is real simple. Computer tells valve to open and close rapidly. Valve opens and closes rapidly. If valve does not do that fast enough, then an error code is created. Only three things in that circuit - computer, wire, and valve.

How I would have responded? I would have asked why they knew the computer was defective. I never mention the IACV. Let them mention the valve and why they know the $200 valve is not defective. I have found only some mechanics who really know their stuff because the word why is used heavily. The stuff I do not know then gets confirmed later with an internet search.

If anyone tells me something without the reasons why and without numbers, then he is lying.

Standing in the dealer to get a new oil filter or wiper blades is very educational. Watching them talk to women quickly separates honest dealers from the shady ones. Numbers (verses no numbers) quickly identifies the honest ones.

Sure, they went through the diagnostic procedure, and when some part that is acting up intermittently, worked at the time, they blamed the PCM.

Diagnostic procedure does not work for intermittent problems. It can only identify a constantly defective part. Intermittents require additional facts.

In a previous discussion, I noted Toyota's biggest problem. People. In this case, the mechanic cannot really be effective if, for example, the exact conditions during every 'failure' are not defined. For example, Cloud later noted that this failure occurred as the car was warming. Also critical are factors such as where the temperature needle on the gauge was located during each failure? Was it accelerating or during constant speed? How many minutes after starting the cold engine? How much gas in the tank? Was air conditioner on? Headlights? Does it happen at night and day? Does it happen when going uphill or down?

Just a short list of what must be provided so that a mechanic can really do his job. A problem because most people cannot bother to collect facts or make the problem reproducible. And because so many people only get angry when asked question after question. So many want intermittent problems solved immediately.

So a mechanic (if not provided an oscilloscope and without information on how to make the problem reproducible) can only keep replacing parts until something works - shotgunning. That will be the solution here.

Check list said if the IACV is not constantly failed, then replace the computer. Check list procedure does not address an IACV failure that occurs, for example, only as the engine gets warm. Only way a mechanic can find / fix that problem is if a person / driver volunteers that fact.

car is back at mechanic. I asked him why didn't he check the Idle Air Control Valve--and he said he did. He said he checked the circuits along the system, manipulated the valve by hand, etc.

So, we'll see. I can't get my inspection sticker with the car like that.

I am shocked SHOCKED that the mechanic performed the checks that tw repeatedly complained he must not have done.

He SAID he performed the checks. How is Cloud to verify that? Guy was like (thought bubble) "hmmm, some friend told her to ask blah blah blah..." (speak bubble) "SURE MA'AM, I did that!"

;)

The mystery unfolds.

Well, I pretty much believe him. He described what he did in much more detail than I put down. And how is anybody supposed to verify actions like that, anyhow?