Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
Check valve timing while checking for loose, stretched or jumped teeth on timing chain. See appropriate article in ENGINES. If no problem exist, replace ECM. ECM is located behind glove box. See Figure. If problem exists, repair or replace components as necessary.