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Code P0138? Getting a check engine light on?

Tiny
CPKAY1
  • MEMBER
  • 2007 TOYOTA RAV4
  • 2.4L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 116,000 MILES
I keep getting a check engine, VSC, and 4WD light on. I have replaced fuel cap, downstream O2 sensor, spark plugs and coils. Where do I go from here?
Friday, September 29th, 2023 AT 3:40 AM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
We only handle one problem per thread so please start a new question for the VSC, and 4WD light on because the Code P0138 will not affect the other warning lights.

Code P0138 in the context of a 2007 Toyota RAV4 (or many other vehicles) refers to "O2 Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 2).

So, with the voltage high it means there is air getting into the system so I would check for an exhaust system leak,

If no leaks are found the next step is to replace the catalytic converter or I have seen people install a spark plug extender where the oxygen sensor goes to help confirm the bad cat. Check out the images (below). Please let us know how it goes.
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Friday, September 29th, 2023 AT 12:27 PM
Tiny
CPKAY1
  • MEMBER
  • 4 POSTS
When I took my RAV4 into the shop, it needed a new muffler, and the check engine light, VSC light and 4wd light were on. I told them to fix it. They put a new muffler on and replaced the Bank 1 Sensor 2. 22 miles later the three lights came back on. The shop did a rescan and got the P0138 code again. They showed me a whole list of things to try but had no solution. I replaced the gas cap, checked vacuum lines, replaced the plugs and coils. The car has 116,000 miles on it. Could the catalytic really be bad?
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Saturday, September 30th, 2023 AT 3:42 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Yep, if you use a spark plug extender and the light stays off then you know the cat is bad.

https://www.autozone.com/ignition-tune-up-and-routine-maintenance/spark-plug-non-fouler/p/dorman-spark-plug-non-fouler-42006/720805_0_0?spps.s=5905&cmpid=LIA:US:EN:AD:NL:1000000:GEN:19502231967&&CATARGETID=120054150001287257&CADevice=c&gclid=Cj0KCQjw1OmoBhDXARIsAAAYGSFqkHQ_ypfF9Gr35HtMAgyWR_d-zDKYshZ4BAXCmG3ASqy1h3Ul9vkaApudEALw_wcB&gclsrc=aw.ds

let me know if the code stays cleared.
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+1
Monday, October 2nd, 2023 AT 9:50 AM
Tiny
CPKAY1
  • MEMBER
  • 4 POSTS
Thank you for your time. If this solves my problem, I will let you know.
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Monday, October 2nd, 2023 AT 10:33 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
It should, good luck with the repair.
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Tuesday, October 3rd, 2023 AT 10:20 AM
Tiny
CPKAY1
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Thanks.
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Tuesday, October 3rd, 2023 AT 11:03 AM

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