» » »

Toyota Q&A

Ask Your Question

1997 Toyota RAV4 Question: PO401 low flow



sophie19920, 2.0L 4 Cylinder, Bath, NY, August 17, 2011, 12:38

replaced VSV & modulator. With EGR tube off and vacuum pump attached modulator port Q,with ing. on no reading. Sometimes I have vac. at Q when ing. is off,wnen turned on I loose Vac. I think maybe i have a prob. with the connection at the VSV. What should the voltage at the VSV connection? codes (2) both po401


1 Answer
Flag This
  • Answer #1

    August 18, 2011, 15:50

    I would go to this link and follow this article. I wrote this as I do Emissions Diagnosis and Repair at a Gold Shield Station in Calif. A P0401 is somewhat common on Toyota and they can be stubborn to resolve. The passages have to be 'perfecto' clean and I have seen a few of the vacuum solenoids fail on an intermittent basis. It is common for the transducer to become weak as well.


    Flag This