Check Engine Light

Tiny
CUTEANDSASSY
  • MEMBER
  • 2005 MITSUBISHI ENDEAVOR
  • 130,000 MILES
My check engine light came on and took to Auto Zone to have them check and got this print out~
~ Idle control system RPM lower than expected
1. Large vac leak on engine
2. Throttle body cond -dirty
3. Faulty IAC valve/throttle body

One salesman tells me to put a bottle of this fuel injection cleaner in it w bout 3/4 to full tank of gas and should clear it up
One salesman tells be to spray something I forgot the name of it on engine and it would tell me if I have a leak.

Not sure? Help!
Friday, May 3rd, 2013 AT 9:22 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,912 POSTS
First you have to understand that diagnostic fault codes never say to replace parts or that they're bad, so forget number 3. Next, it is very unlikely a magic "mechanic-in-a-can" is going to fix a mechanical problem, so forget number 1 and 2.

Fault codes only indicate the circuit or system that needs further diagnosis. About half of the time there is some other cause besides the sensor referenced in the code. There could be a broken wire, a corroded splice, or a corroded terminal in an electrical connector. There is no fault code that indicates a vacuum leak. The vacuum leak is one possible cause of setting a code but it's that cause that needs to be diagnosed. It sounds like they're giving you the diagnosis after just reading the codes. Mechanics read the same codes, do the necessary diagnostics, THEN determine the solutions. Your parts guys skipped a step.

You need to get the exact code numbers or descriptions, then we can suggest some tests to narrow down the cause of the problem. You can go here:

https://www.2carpros.com/trouble_codes/obd2/P0100

to get an idea of what the typical descriptions look like.
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Friday, May 3rd, 2013 AT 10:17 PM

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