2004 Toyota Camry - Coil pack issues

Coil packs keep going out. Possible back pressure from Catalytic Converter/exhaust issues? although the catalytic converter was replaced by dealership. After catalytic converter was replaced car still had very little power especially going up hill. When going up hill and accelerate more to get up hill faster, check engine light blinks and then stays on from possible blown coil pack. Mechanics are stumped

That’s a first.

How do you know coil packs are going out?

Coil packs may go after age or some kind of short. I’ve had to replace only ONE on the vehicles we’ve owned that have coil packs in the past 17 years.

Get new mechanic


Could be an intermittent problem with the wiring to the coil.
Have the “bad” coils been tested and confirmed failed?

Coil packs confirmed as bad. Mechanic keeps replacing without charging me. Problem committing continues, 3 mechanics including dealership cannot determine why this continues

How many miles has it been since the spark plugs were changed?

Any description of how they fail? How they were tested?
It’s not easy to kill a coil; I don’t see how a mechanical engine problem would kill a coil.
Has to be an issue with the plugs or the coil electrical supply or drive.

You’re fortunate or you don’t own a Toyota. I’ve replaced three on my Corolla. In fact it’s a known issue.

As far as the OP’s vehicle is concerned, this is way out there but is it possible a partially clogged catalytic converter is making the coils work harder and burn out prematurely?

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In the past 16 years I’ve owned a 2005 4Runner (sold at over 300k miles). Wife owns a 2007 Lexus ES-350 (has over 250k miles) and I currently own a 2014 Highlander(little shy of 150k miles).

Plugs, wires everything has been changed. New timing chain.

How do the new plugs look? Are they fouled?
Wonder how many miles on the car/engine and why the chain was changed?

Each engine available in this vehicle have individual coils for each spark plug, no coil packs.

Were all 4 or 6 coils replaced? How many times? Is the repeated coil failure always on the same cylinder?

When you hear hoofbeats look for horses, not zebras. A coil pack burning out because of restricted exhaust would be a zebra.

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So “lucky.” Got it

Frankly, it would probably be more like a unicorn. I did say it was “way out there.”

You have stats to say it’s luck? Show me.

It is not always the same coil. All have been replaced. As far as the other person’s zebra/ horse reference, I’m not sure that is a clear understandable assessment.

I suggest you have the alternator output checked. Make sure the DC output is good along with checking for excessive AC ripple voltage. The AC ripple should be less than .1 volt.

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Just spoke with dealership and they are clueless.

“Just spoke to The sealership and they are clueless”

That sounds like the truth. Proper use of a vacuum gauge (which nobody seems to use anymore) will quickly reveal if the exhaust is restricted.

Your car is misfiring under a heavy load. If you have enough miles to wear out a timing chain, how is the engine compression? No band aid will fix a worn out engine. I have a 2012 Camry and my daughter has a 2010 Corolla other daughter is on her second RAV4.

No coil replacement with any, no reports of coil replacement from friends with Toyota’s. Guess we are all lucky.

I have replaced many ignition coils on Toyota engines. Coil failure will set a P0351-P0356 fault, nothing to do with the exhaust system.

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