How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Ron Z. Your Own Question
Ron Z.
Ron Z., - Toyota Tech -
Category: Toyota
Satisfied Customers: 18871
Experience:  18+yrs experience. State Inspector and Toyota Diagnostics
Type Your Toyota Question Here...
Ron Z. is online now
A new question is answered every 9 seconds

HIghlander: I have a 2003 Highlander, V6 all wheel drive.

This answer was rated:

I have a 2003 Highlander, V6 all wheel drive. My check engine light came on and I went to Autozone, they ran their diagnostic and I got three codes; P1135, P0446 and P0440 - they told me it was an O2 sensor that needs to be replaced -Bank 1 Sensor 1 - does that sound right?
Hello! Welcome to the site! Thanks for coming! I'm Ron Z. I'm here to provide as much info and insight as I can, to best answer your question.

Can you re-check the P0440 code. This is not a valid code for this year/model vehicle. Perhaps it was P0441?

Customer: replied 3 years ago.

The print out that Autozone gave me says P0440, P0446 and P1135

OK. AutoZone uses a "generic" scan-tool, so the P0440 is more than likely just a by-product of the P0446 (the P0440 is not a valid code on this vehicle, however, it IS on other vehicles, and is very similar to the P0446).

Ok... anyway...

Looks like you have 2 different problems here.

The P1135 is a very straight forward code pointing to a faulty A/F Sensor (very similar to an Oxygen Sensor, just "smarter" as Toyota uses it's inputs for more functions). This is a very common Toyota fail item. The sensor is located on the side of the engine closest to the windshield, mounted to the exhaust manifold. Carefully inspect the electrical connector and as far up the harness as you can looking for any loose, broken or damaged wires (very rare, but always good to check!). If the visual inspection checks ok, replacing the A/F Sensor will solve the problem. Keep in mind- it must be an "A/F Sensor" and Oxygen Sensor will not do the job correctly!
The P0446/P0440 is a bit more difficult to diagnose. P0446 is recorded by the ECM when there is an evaporative emissions leak from the components within the EVAP system, or when there is a malfunction in the VSV for EVAP, the VSV for pressure switching valve or in the vapor pressure sensor itself. Best place to start here is to have the EVAP System "smoked". This is where a machine forces smoke through the system, and any leaks will reveal themselves. If the smoke test shows no leaks, then unfortunately, each item listed above will need to be tested. More times than not, it's a faulty VSV, so these should be tested first.

Please remember the website WILL NOT automatically compensate me with a part of your deposit or from your subscription WITHOUT YOUR RATING! Please use the Rating System and *Rate My Service* if the information/advice I supplied has helped you. If you have any more questions, use the "Reply" tab – I'm always happy to answer follow-ups! Follow-ups are always FREE! Even after you rate! Thank-you!

Ron Z. and 3 other Toyota Specialists are ready to help you