One problem related to radiator has been reported for the 2006 Toyota RAV4. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Toyota RAV4 based on all problems reported for the 2006 RAV4.
We were on the road (on a family vacation). The day that we were coming back the check engine light, the vsc light and the slip warning light came on as we were pulling out of the hotel parking lot. On the way to the dealer, I also felt like the car was misfiring. The dealer found "multiple codes p0304, p0305, p0306, p0356, p1578, c1201. #6 coil malfunctioning. Recommend replace #6 coil pack and recheck. Possible that other coil may fail from the result of #6 coil failing. " #6 coil pack was replaced and the Rav4 has been running fine since. The dealer also said that "typically after one coil goes the others follow shortly after", so I will keep an eye open for that. It is strange since ignition coils have a long life expectancy. I checked on-line and there seems to be a high failure rate with coil pack part # 90919-02251, which is the original part that came with the car. I made sure the part was replaced with the latest revision (90919-a2007) of the new part numbers (90919-a2002, 90919-a2004 or 90919-a2007) that Toyota changed to. It is also interesting that most of the failures happen with #6, #4 and #5 coils (in that order). The failures seem to concentrate around the right front corner, which is close to the radiator (hot fluid) exit. Maybe that is why the later revision part # coil packs have a double metallic screen outside the plastic housing, to protect the assembly.