Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

$6000 repair on 2006 Toyota Sienna AWD

Check engine light and a few others came on so my husband took it to the dealer who told him two and probably three catalytic converters needed replacing. Cost $6000 in parts, not including labor. The car has 142,000 miles and he also advised replacing the timing belt and added that we should change the spark plugs at a cost of $425. This all seems ridiculously expensive. Anyone else have a catalytic converter problem like this? Any advice?

If memory serves me correctly, the Sienna’s converters are expensive because they are manifold converters - they are integrated into the exhaust manifolds. That van has two of those, plus another cat further down the exhaust.

Sorry for your troubles, but if the timing belt has not been changed it’s about 52000 miles overdue. The change interval for an 06 is 7yr/90k miles (which ever comes first). I would get an estimate from a different dealer or mechanic though. I’m having the timing belt replaced on my wife’s 06 Sienna in the spring at 60k miles. To the best of my knowledge the 3.3 V6 is an interference engine.

I’m a little unclear on the post. Did you already spend 6k for the repair or just get an estimate? If not, get a second estimate from an independent mechanic before authorizing the work.

Ed B.

Please tell us what your owner’s manual says about the timing belt and the spark plugs. Also tell us if those items have been replaced on schedule so far.

I’d trade it in for another car. Don’t put $6000 into this one.

You can try an independent mechanic to see if he also feels all the cats need to be replaced. If the timing belt has never been replaced and the spark plugs are OEM too then the van hasn’t been maintained well and better to let it go and get another car.

“I’d trade it in for another car. Don’t put $6000 into this one.”


If the timing belt has never been changed previously, then that is likely to be an illustration of the general maintenance that this vehicle has received over the past 7 years. For example, if the trans fluid has never been changed, the trans is most likely due to failure in the next year or so, and that would mean the expenditure of another $2,000 or so. Ergo–lack of maintenance has likely made this vehicle into a ticking time bomb waiting to explode in the owner’s wallet.

A poorly-maintained vehicle is not a good candidate for major “investments”, so it is probably more cost-effective to dump it, buy a new vehicle, and then maintain the new one at least as well as the mfr specifies. (Note: If the vehicle has actually been maintained totally in accordance with the mfr’s maintenance schedule, then I apologize for my assumptions.)

If the spark plugs and timing belt were previously replaced in the 90k-100k range, then there’s no need to worry about them till you approach the 200k range. If they haven’t been changed yet, then that’s routine maintenance that should be done.

As for the catalytic converters, I would definitely get a 2nd opinion from an independent mechanic. If your O2 sensors haven’t been replaced yet, there’s a good chance that’s all you need.

If, after an independent mechanic looks at it, you’re still staring at a “$6000 + labor” repair bill, then you have a tough decision to make which will depend on your finances and vehicle needs. These vehicles are reliable and can last a long time. But that is a lot of money to put into a used car.

It would be very strange for all you cat converters to fail, I would get a second opinion. Is the van suffering from loss of power?

Get two more opinions on the CEL from good independent mechanics. If you don’t know one, ask friends, neighbors, and coworkers for recommendations. A few will be mentioned several times. Try them. If it turns out that the cost is still several thousand dollars, then take it to a Toyota dealer or CarMax (they are the same near me) and see what they will pay for it as a sale; not a trade-in. Then you can decide whether to sell it to them or trade it when you search for a new car.

Unless there is an emissions test in your immediate future, the converter problem, if indeed there is one, can be deferred indefinitely…The OP stated that the CEL plus other warning lights came on…WHAT other warning lights?? Also, did the $425 estimate include both a plug change AND the timing belt?? If so that’s not too bad…And finally, you don’t have to take your vehicle to the dealer to have repairs like this performed…

I’d like to know what the code is. If its a P0420 code, you probably only need a rear oxygen sensor and not new cats. Dealer are bad about that when they know the cats are not the problem.

I also agree with Uncle Turbo. This may be the right time to trade. A dealer can fix the car much cheaper then you can and the trade in value, assuming everything else is OK, may make it worthwhile.

Here is what the print out from the deal says:
T=1.0 Vehicle has codes PO420 and PO430. B-1 & B-2 Cats insufficient. Checked for exhaust leaks and saw non. checked all 02 & A/F Sensors and all are plugged in. Ran vehicle in air at 2500-3000RPMS and rear 02.S are following the fronts. See est on new cats which the two front ones are part of manifolds and it is AWD so rack has to be moved and then veh aligned. Costs: Replace all cats $3085.47 Sensors, if nec $874.55, Alignment $80. Timing Belts $506, Water Pump if needed $324, Intermite Shaft $474, Tranny Flush $245, Spark Plugs $456. I don’t think the timing belts have not been changed but plugs have been by my local mechanic. I will check my records to be sure. I live 40 miles from a Toyota dealer.

My daughter is due with our first grandchild and lives 200 miles away. We’re suppose to leave for be with her as soon as she calls. Can or should I drive this car?

Yes, you can drive the van. You can also get significantly better prices for most of the services. It is worth at least $7500 in trade and $8600 as a private sale in clean condition. Take $6000 off either and you have a general idea what your Sienna is worth. I would offer it for sale to a car dealer (not necessarily Toyota) and see what they offer you.

Failed catalysts are often the result of misfires, leaking injectors, blown headgaskets, overheating, etc. I would make absolutely sure ALL possible problems are resolved before springing for new cats

Cats can fail in various way, but one of the most common is they get plugged up and don’t pass the exhaust gas freely. Mechanics can usually test for this without removing the cat. They remove the upstream O2 sensor and measure the exhaust pressure with a pressure guage. If the cat is plugged, there will be higher upstream pressure than normal. It might be worth it to ask your mechanic if it makes sense to have this test done. I expect the test isn’t overly expensive. Certainly much less than a cat replacement.

@GeorgeSanJose cats only have to be marginally degraded to set P0420 and P0420.
Assuming the cat is actually the problem.
Backpressure testing is good for detecting extremely plugged cats.

Toyota’s are real bad for those codes for some reason and it is rarely fixed by replacing the cats, it is usually fixed by replacing the rear O2 (A/F) sensor(s). Look for a good independent mechanic, but if you replace the rear sensors, order them from the dealer using your VIN number to make sure you get the right one.