Check Engine + VSC = Code P0420

Asked by Feb 16, 2016 at 07:20 AM about the 2004 Toyota Highlander Base V6 AWD

Question type: Maintenance & Repair

I recently purchased this car, and today the check
engine light and VSC came on. I had Advance Auto
scan it and it came up with P0420. What are some
troubleshooting steps I can do before taking it in to
possibly replace the exhaust or cat? Other possible
reasons for this?

2 Answers

12,410

It wouldn't hurt to test fuel pressure to make sure you don't have leaky fuel injectors. unburned fuel can cause this problem too. also, the o2 sensors can be tested. It might not hurt to have the exhaust inspected and "sniffed " by a good muffler shop. this could give you a better picture of what is going on.

1 of 1 people found this helpful.
12,410

as far as the vsc code, you are going to need a more extensive scan than the little code reader that the auto parts stores use. It wouldn't hurt to have a quality shop scan it with their professional equipment. they can read "live data". this means that they can assess while the engine is running and give a good pic of all systems while they are operating.

Your Answer

Toyota Highlander Experts

  • #1
    Wendy Tucker
    Reputation
    4,550
  • #2
    Tom Demyan
    Reputation
    4,040
  • #3
    Shawntele Lewis
    Reputation
    2,470
View All

Related Models For Sale

Used Honda Pilot
531 Great Deals out of 40,010 listings starting at $300
Used Toyota 4Runner
341 Great Deals out of 25,359 listings starting at $1,750
Used Toyota RAV4
751 Great Deals out of 50,464 listings starting at $1,195
Used Acura MDX
412 Great Deals out of 16,499 listings starting at $2,000
Used Toyota Camry
954 Great Deals out of 90,171 listings starting at $300
Used Honda CR-V
722 Great Deals out of 58,894 listings starting at $999
Used Ford Explorer
1,037 Great Deals out of 70,318 listings starting at $2,100
Used Toyota Sienna
475 Great Deals out of 26,039 listings starting at $1,250
Used Nissan Pathfinder
439 Great Deals out of 26,081 listings starting at $2,500
Used Toyota Tacoma
669 Great Deals out of 45,898 listings starting at $2,700
Used Toyota Sequoia
125 Great Deals out of 5,374 listings starting at $1,999
Used Jeep Grand Cherokee
946 Great Deals out of 72,164 listings starting at $1,200

Used Cars For Sale

2018 Toyota Highlander For Sale
15,577 listings starting at $23,882
2017 Toyota Highlander For Sale
20 Great Deals out of 6,167 listings starting at $26,988
2016 Toyota Highlander For Sale
62 Great Deals out of 1,732 listings starting at $21,787
2015 Toyota Highlander For Sale
126 Great Deals out of 3,330 listings starting at $19,000
2014 Toyota Highlander For Sale
55 Great Deals out of 1,066 listings starting at $14,899

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.