I recently purchased a 2nd hand Kia Rio LX 2018 with 24k miles on the clock. The car drives well, the check-engine light is off, I had a pre-purchase inspection done on it (Lemon Squad) and their report came back with no real problems except for an OBD scan code of P0638.

I also went ahead and bought a scanner myself and mine gave got the same P0638 reading, but after taking the car to an Kia service center they told me that they found no code showing up for them, and that the reason for the code showing up on the two non-Kia scanners is because the scanners are generic, and that the car is completely fine.

FWIW, the scanner I bought was the Innova CarScan Advisor 5210 while the LemonSquad report included a photo of a Matco Tools MD1200 which is generic too.

I looked online and I can't find any other reportings of generic scanners giving incorrect readings though. I want to believe the service center because that means the car is fine - it looks like fixing the problem could be a significant amount of work in the worst case scenario - but I'm hesitant to just believe that this the whole of it especially because the P0638 code is potentially pretty serious from what I see online.

Can anyone here help me out here and let me know if everything is fine or if I should try to find another service center to address this issue?

  • Welcome to Motor Vehicle Maintenance & Repair! Neither the Innova nor the Matco scanners are "generic". Both are name brand tools. I would trust either one implicitly with what they report. Just because they aren't Kia's own scanners doesn't mean they aren't good and accurate scanners. I have two different Innova scanners myself (one for OBDI and one for OBDII). Never had an issue with either. Something to check is, does the check engine light actually work? It should illuminate when you turn the car on. Could be the light has been disabled via electrical tape, but who knows. Commented Jul 9, 2021 at 19:58
  • Thanks, makes sense. Yes, the light does come on when I turn the car on.
    – PKO
    Commented Jul 9, 2021 at 20:00
  • Thinking about it more with your feedback I'm going to look for another place to check the car out. It struck me as weird that things wouldn't be standardized decently but not having access to their equipment I have no way of assessing things directly. Appreciate the feedback.
    – PKO
    Commented Jul 9, 2021 at 20:06
  • Some scanners just don’t like certain cars - many scanners will not communicate with jaguars, which is why I bought one which is known to work on jags. So, check elsewhere but I don’t see why the dealer would lie to you to say there is no fault. OTOH some places have been known to make false reports of work needed...
    – Solar Mike
    Commented Jul 9, 2021 at 21:21
  • TBH, I'm out of my depth here. FWIW Amazon's interface explicitly says that this fits my vehicle (when buying the Innova scanner the site shows several dropdowns to select your vehicle's exact make/model/trim/engine etc) and they do claim that it is supported. I could work with "didn't communicate/no reading" but the OBD-2 codes from what I read online so far don't leave room for misinterpretation. Could fixing a P0638 issue be really tricky or daunting or work intensive with lots of room for headaches?
    – PKO
    Commented Jul 10, 2021 at 3:16


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