Ignition coil getting burned out

Prius has a separate spark igniter for each spark plug. If you take a look at the top of the engine, you will see four dark rectangular assemblies mounted to the cylinder head cover. Those are the tops of the spark igniters.

Water can drip down from the cowl above the engine, onto the engine. If this happens and if the rubber seal on the igniter is not working, then water will enter the spark plug well. Only one small bolt holds the igniter to the cylinder head cover, so it is easy for water to get in. [This is one reason why using copious amounts of water to wash the engine is a really bad idea, although I know you did not do so.]

If water gets into the spark plug well, this will cause spark plug misfiring and damage to the spark igniter. Hence, the driveability issues that you noticed. Toyota issued a TSB on this condition; see attached file.

• How many spark igniters were replaced?
• Was it necessary to replace the spark plugs as well?
• Did you take a look at the replaced parts; if so what did they look like? Did you see corrosion on the bottom of the igniter?
• What did you pay for the repair?

 

There was a technical service note about a problem with water getting in the ignition wiring and spark plug wells. I don't know the number but this is exactly the expected failure mode.

Bob Wilson

 

I had to pay for two coils and two plugs after a particularly rainy highway trip last fall. No extended warranty, and Toyota refused to cover it. Apparently there was a service bulletin or something about a hood seal near the wipers, but they claimed to know nothing about it. One of my neighbours teased me once about not being able to drive an electric car in the rain. I thought it was funny at the time.

 

Yes, if you are interested in reading the TSB, I attached it to a prior message in this string. Please note that the existence of a TSB does not mean that the problem is automatically covered under warranty.

 

Thanks, Patrick. I've printed it out and will be plugging that gap. Still, I find it extremely annoying that I'm on the hook for a $500 repair which could have been avoided had Toyota taken responsibility for its own errors.

 

Re: Ignition coil getting burned out - Mine too, but '07

I have a 2007 Prius and it's in the shop and the techs are stumped -- the code said to replace the ignition coil, so they did that. They took it on a test drive and it died within two miles. They restarted it and brought it back to the shop. Took it on a 20-mile test drive adn couldn't get it to die again, but don't feel the car is "fixed," so they still have it.

Any ideas? Here's what led up to this: Two weekends in a row, I got the "triangle of death" and check engine light. The car would hesitate and shudder and not really respond when I hit the accelerator. I'd have to pull over, turn it off and re-start it again to get home. After letting it sit, the warning lights would go away. Finally brought in in on Monday and now it's Wednesday and no solutions. Help!

 

I have just checked an error message on my 04 Prius and gotten a P0301 message.
I believe the warrantee is 3 yrs / 36000 miles - whichever comes first, so I am out of warrantee
Can anyone give me any indication as to how to verify this before I squander money on Toyota 'fixing' a design fault (If it is in fact the same problem)

 

anyone?

 

DTC P0301 means that cyl #1 is misfiring. This is the cylinder that is closest to the fender (driver's side, since you have a RHD UK model.)

If you want to try to determine the cause of the misfire yourself, then you will first need to remove the igniter wiring harness connector. Take a look at the connector to see if there's any corrosion within it, or on the igniter socket.

Then remove the igniter and look at the high voltage terminal to see if it is corroded. Also look at the body of the igniter to see if there are any cracks or burn marks. If so, then replace the igniter.

Then remove the spark plug and inspect it. If any problems, buy the correct iridium spark plug replacement (you'd might as well replace the other three plugs while you are at it.)

If you should find the igniter and spark plug are fine, and there's no evidence of water in the spark plug well, then check the wiring harness connector leading to fuel injector #1 and see if it is loose or has any corrosion. If the wiring connection is sound, then maybe the injector has to be replaced. This is not very easy to do because you will first have to release fuel line pressure, then remove the valve cover, then remove the fuel line in order to replace the injector.

Good luck.

 

Aaaarrrgghhhh!!! You're scaring the living daylights out of me - I am a computer geek . . . not a mechanic . . but I do generally fair pretty well fixing things . . .

Please be patient with me, I am trying my best . .

down your list. (night time now, so below is all from memory from a quick peek under the hood this afternoon)

igniter wiring harness connector - I assume this is the connection right above the spark plug - furthest left - Does it just unclip? or is the connector further down the line?

high voltage terminal - I am guessing this is the point where the wiring harness hits the spark?

Spark plug - If I am replacing, I will do all 4 at once

I'd imagine the above list should be easy enough - only tools required - 1 spanner(size 10ish I guess), spark socket, torque wrench maybe?

Thanks - this has been helpful - will have a crack tomorrow evening.

 

Yes, cyl #1 is to your left when standing at the front bumper and looking at the engine. Note the connector color alternates between black and grey as you look at the four igniters, and see the locking tab on the connector that you depress to release it.

Once you have removed the igniter, look at the bottom and you will see the high voltage terminal recessed within.

You will need a 16 mm spark plug socket. 10 mm sounds right for the small igniter bolt. Tightening torque is 18 N-m or 13 ft.-lb for the spark plug and 9 N-m or 82 in.-lb for the igniter bolt.

When you reconnect the igniter wiring harness connector, make sure that it is fully engaged and you hear a little click as the locking tab locks in place.

 

i've had to replace 1 coil so far.. it's exactly as you describe. if you unplug the coil to find out which one is misfiring, you'll probably find that 1 will not change the effect. however.. if 1 isn't fireing and you unclip another, the prius will shut down and error code for an ignition coil being unplugged or harness unplug.. depending on how you do it.

 

Looks like I am late getting in on this. Hope someone see it. Yesterday ALL of the lights on my dash came on. I was able to get to the dealer and they told me that it was an ignition coil and that I would be fine for the weekend, bring it back Monday. I left the dealer and promptly broke down, in traffic, on a busy street, at 3pm. Not a good day for me. I now have a loaner, hard with two car seats, and my warranty is out. I am very worried about what this will cost me.

Someone mentioned earlier about water in the engine. This happened to me last summer and left me stranded at work. Tell me again (before I go to pick it up from the shop) how these two things are related? I would like to sound intelligent when I go in.

Thank you!

 

It is possible for water to drip down from the cowl that runs across the back of the engine compartment. The windshield wiper motor is within this cowl and the wiper arms are attached to the cowl. Water may drip onto the engine valve cover.

The four spark igniters and four spark plugs are located deep within the valve cover. If water drips on the engine valve cover, it might then seep into a spark plug well that the igniter and spark plug are located within.

In that case, the water will cause high voltage produced by the igniter to leak to ground rather than produce a spark at the spark plug tip. If this happens the engine will misfire.

I am really surprised that if your dealer determined that the spark igniter (aka ignition coil) had failed, that this was not replaced for you immediately. The Prius engine will run very poorly on only three cylinders.

 

Thanks! I am reading up on all this for when I go back to pick it up. I am a little upset that something like this can happen. My Prius only has 53000 miles on it and I expected that this is a problem I would face much later in the cars life.

Is there any way to fix the leaking problem. Seem to me that there should be a better seal there. The dealer said that they are not seeing this problem.

 

If your car has this leaky cowl problem, the solution is to put a small bead of black sealant on the cowl gap, where a foam gasket currently exists. See the TSB attached to my post #2 above.

 

Hey, thanks for the info. I am suspecting a bad ignition coil. I replaced my spark plugs and still getting some hesitation and a little rough running. I Put the engine in test mode. I tried unplugging all of the coils one at a time, the engine stopped after 2 or 3 seconds. I thought I was narrowing it down, but the same thing happened on all four coils. #4 ran maybe a second longer. Does that seem right? I thought the engine would run with only one coil unplugged. I did get the error symbol in the upper left corner of the display each time. Then I put the engine back in test mode each time. Thanks, Jon