1999 Toyota Sienna V6 Fault Codes P0340, P0300, P0302, and P0305 - Diagnosis and Repair Guide

Model: 1999 Sienna V6 Fault Code: P0300 Posted: 2009-03-22 17:33

Hi everyone, I'm new to this forum and seeking help with a recurring engine light issue on my 1999 Toyota Sienna V6. The check engine light comes on intermittently and then goes off after a few days. I've used an OBD2 scanner to retrieve fault codes, which show P0340, P0300, P0302, and P0305. My van has only accumulated 115,000 km, and I have not yet replaced the spark plugs. Given these codes, what could be causing the issue? How can I accurately diagnose and fix the underlying problem? Any advice or troubleshooting steps would be greatly appreciated! Thank you in advance for your insights.