Good morning Sienna owners. I have a 2000 Sienna XLE with 189,023 miles, my check engine light starting flashing while on the freeway going about 78 mph. The following codes have shown up P0300, P0304, P0305 & P0306. The dealership checked my plugs and coils and they are old but working fine with a resistance of 1.25 ohms approx. across all wires. They stated they unplugged fuel injector and vehicle ran worse without them. The think it might be intake/exhaust valves and suggested compression check with leakdown too. Has anyone had a similar issues and ideas before I shell out another $200.00 for compression check with mechanic, thank you for any inputs.
Do I get it Fixed or cut my losses
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In my opinion, it depends. Have you owned this vehicle all its life and maintained it? If so, fix it because you know it's a good vehicle and money is only going to drip out of your pocket to keep it running - these vehicles can go close to 300k.
Have you bought it fairly recently with an unknown maintenance history? If so, diagnose it - it might be a good vehicle with just a minor maintenance issue (you need to find a good mechanic that specializes in high-mileage toyotas). Have a trusted toyota mechanic work up a pre-purchase inspection to see everything that it might need and a general condition of the vehicle.
Have you owned it for a long period of time and put as little maintenance into as possible? If so, cut your losses - it's probably going to be a money pit.
Now, regarding your actual problem, if the plugs and coils are fine, it's probably a fuel or air issue. That means check fuel pressure (and maybe upstream O2 sensors). 4 is the DS rear cylinder, 5 is the front center cylinder, and 6 is the DS front cylinder. Good luck!
Have you bought it fairly recently with an unknown maintenance history? If so, diagnose it - it might be a good vehicle with just a minor maintenance issue (you need to find a good mechanic that specializes in high-mileage toyotas). Have a trusted toyota mechanic work up a pre-purchase inspection to see everything that it might need and a general condition of the vehicle.
Have you owned it for a long period of time and put as little maintenance into as possible? If so, cut your losses - it's probably going to be a money pit.
Now, regarding your actual problem, if the plugs and coils are fine, it's probably a fuel or air issue. That means check fuel pressure (and maybe upstream O2 sensors). 4 is the DS rear cylinder, 5 is the front center cylinder, and 6 is the DS front cylinder. Good luck!
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I haver a 2001 Sienna with 451,000 miles. I don't have your problem but the mechanic will need to do a compression test to rule out serious engine issues. If the vehicle has been well maintained then some fix is cost effective in this car purchasing environment. One question what symptoms does your vehicle present. Also I would never push a twenty two year old vehicle 78 mph on the road if you want it to last. A blown head gasket or cylinder damage will be bad. A fuel injector or oxygen sensor replacement will be preferable. Make sure the wires to the spark plugs have been evaluated .Mine doesn't have any but I believe yours has some to the ones on the firewall. Cylinders 1,3,5. Good luck.
$200 leak down and compression test on that engine is a super bargain but I suspect it's something else. Having mechanical defects on both banks are highly unlikely.
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