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Ignition coil repair

Discussion in 'Gen II Prius Technical Discussion' started by jimmy bob, Feb 2, 2010.

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  1. jimmy bob

    jimmy bob New Member

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    Hello,

    I recently have had a problem with my 2005 prius in which the check engine light came on and there has been a lot of shuddering upon acceleration. I took it to a mechanic who diagnosed the problem as the ignition coils.
    Do you really need to replace all 4? Also, has anyone replaced these coils on there own? How do you do it? From what I have been reading they sit right on top of the spark plugs so it seems like I could do the fix myself.

    Any help is appreciated!

    Thanks!
  2. jelloslug

    jelloslug It buffed right out!

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    You can replace just one of them. They are right on top of the valve cover but I'm fairly certain that you have to remove the windshield wiper cowl to get to them. It's not a tough job but a little time consuming.
  3. jimmy bob

    jimmy bob New Member

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    Thanks! The only problem is, I don't know which one is bad, how do you figure that out on your own?
  4. hyo silver

    hyo silver Awaaaaay

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    I've had two coils and plugs replaced by the dealer, though there's no big reason you couldn't do it on your own. The error code should tell you which one to replace. When you're putting the windshield cowling back on, be sure to seal it up properly to keep the problem from occurring again. A service bulletin was issued for sealing the cowling, which was not done properly at the factory.
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, you could do the repair yourself, and it is not even necessary to remove the cowl panels.

    First, remove the relay box mounted to the cowl. That will give you enough clearance to access the four igniters. Then remove the wiring harness connectors leading to the igniters and the little bolts that attach the igniters to the valve cover.

    Now, pull up on each igniter and examine each one carefully, looking for rust stains, cracking on the plastic body, and corrosion on the electrical connectors. Replace any igniter with visible faults.

    In the unlikely event that you can't find any igniters with visible faults, then you will have to retrieve the DTC logged by the engine ECU. P030x is the ignition misfire code, where x will equal 1 to 4 depending on what cylinder is misfiring (0 is a non-specific misfire). Cylinder 1 is closest to the passenger side.

    Also remove the iridium spark plugs while the igniters are out, and see whether there's any rust on the spark plug metal shell (which is more evidence that water leaked into the spark plug well.) If so, replace the spark plug and keep track of which spark plug well had the leak. If your car has more than 60K miles, and you need to replace a spark plug, I'd recommend you replace them all while you are at it using the correct Denso or NGK iridium plugs.

    Tightening torque is 82 in.-lb for the bolts that secure the igniters, 74 in.-lb for the bolts that secure the relay box, and 13 ft-lb for the spark plugs. Do not overtighten the igniter bolts as it is very easy to strip the threads on the aluminum valve cover.

    Once you put everything back together, put the Prius into inspection mode and see if the engine runs smoothly.

    Finally, if you had a problem with water leakage, put a bead of sealant on the plastic cowl cover at the center where the two pieces meet, to reduce the likelihood that water will seep down onto the valve cover.
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  6. jimmy bob

    jimmy bob New Member

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    Thank you very much Patrick! This is exactly the info I needed! I'll post the results!
  7. hyo silver

    hyo silver Awaaaaay

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    Yes, that's a much better answer, Patrick. :)
  8. David Beale

    David Beale Senior Member

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    If you can't find any coils that might need replacing, you can just take the new coil, and replace one. Run the engine. If it's now smooth that was the bad one. If it's rough, use the replaced coil in the second cylinder. Keep moving along until it runs smoothly. If it just gets a bit better, then you may have two bad coils.

    If you pull the plugs DO use anti-seize compound on the plug threads. Just a little. Too much may contaminate something else.
  9. Verbosity1

    Verbosity1 New Member

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    My first post on this forum (yay!).

    We just purchased a used 100k 2004 Prius, and in the first week, when going from electric only mode to electric+Combustion, CEL plus a bucking type feeling and loss of acceleration power. After checking it out, had a code for misfire on cylinder 2, and water atop the cylinder 2 spark plug (sounds precisely like the primary problem described in the Toyota Technical bulletin for the 2004-2005 Prius.

    (TSB_EG063-05_water_misfire)

    Looks like online, the ignition coils are from around $45-$85.

    I'm coming from a background of having worked on my old E36 BMW M3. On those cars, the coils had replaceable sleeves for the coils (cheaper).

    Does anyone know if the cowels on the later model Prius' have the same problem? (2006+)

    I'd post links to the Toyota techinical bulletin, but I don't have enough posts yet :) I have it (google docs) if anyone needs it (feel free to message me).

    I was very concerned at first when I saw what I thought was coolant atop a spark plug (thought, bad head gasket, so, this is actually a bit of a relief :D
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    As you know, the TSB applies to 2004-2005 model years. However its possible for a later model Prius to have the same problem of water entering a spark plug well. In that case, the seam between the two black plastic cowl covers is the first area that I would look at, and seal with caulk if needed.

    Another way that water could enter a spark plug well is if the engine had been steam cleaned.
  11. LeadingEdgeBoomer

    LeadingEdgeBoomer Member

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    From another carmaker's perspective: I had at least one bad coil in my 2001 Audi A4 a couple of years ago, and had all four replaced upon the advice of my independent mechanic, who had seen many such failures in this model. Later, I got a recall notice from Audi about defective coils and, since I had done the repair, they cut me a check that covered the cost (keep your records!). So, why is this not yet a recall by Toyota? While I have been disappointed in my Audi's overall reliability (my only complaint), in this instance they did the right thing.
  12. V8Cobrakid

    V8Cobrakid Green Handyman

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    i've changed out 1 coil on my 04 prius. it was running rough, so i started to look into it. i did a little test; pull off the top cables till you find which cylinder it is. you'll know because the sound doesn't change. if you pull a good cylinder, the engine shuts off with warning lights.

    restart the car if it shuts off. (plug in the cable 1st)

    during this time, i realized that hard cornering drops the voltage in the steering unit which also sets off an alarm. i don't remember the codes for it.
  13. Verbosity1

    Verbosity1 New Member

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    Thanks for the information Patrick. I'm 99.9% positive that the engine was steam cleaned, and 99.9% sure it was steam cleaned at the dealership that sold it to me (although, as to which water got in-betweeen the coil and the plug, probably difficult to prove).

    In any event, it's good to know what the permanent fixes seem to be.

    Same assertion by me LeadingEdgeBoomer, this to me? should have been a recall (as opposed to a TSB). If it was something minor, not critical, no big deal, understandable. But when my wife has to call me, and get the car towed because of something like this (sigh), ...just frustrating.

    Hopefully getting the car back today (from the dealership we bought it from). I'm going to in turn talk to the local service department (not that it will likely change anything).

    Here's to hoping this is the last of the purchase (immediate/common problems).

    I ordered the Bentley Prius service Manual ($45) from amazon, hoping this will do for me what it did for my last car (was pretty decent).
  14. oleknz

    oleknz New Member

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    I am having exactly the same problem as JIMMY BOB.



    I had one ignition coil replaced by the dealership (for $277.58) based on the code error DTCS P0301., C1249. That would mean coil on the cylinder #1, right?
    Patrick Wong is saying that the Cylinder 1 is closest to the passenger side. Can anyone confirm that for sure????
    I am asking that because clearly the one that they replaced is the first on the driver side!!!

    Now, if I am on the right track and would probably try to replace any bad ignition coils myself and maybe would have to seal that windshield cowl, can anybody post a photo of the area that needs to be sealed? or point to a photo somewhere on the web?
  15. V8Cobrakid

    V8Cobrakid Green Handyman

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    an ignition coil for how much?... they cost 80 dollars at an automotive store...
  16. oleknz

    oleknz New Member

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    at pep boys they can order one for me for about $90. In Culver City, CA. But I didn't go to the dealership service myself but my friend did when I was away from the country. I called to let her know I didn't want the service for this much (which BTW included changing cabin air filter for $89.99) but they had already installed the coil. - and as I am understanding not even the right one.
    God thanks we have PriusChat.com
  17. Patrick Wong

    Patrick Wong DIY Enthusiast

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    With an inline gasoline engine, the cylinder numbering usually starts from the front of the engine. The rear of the engine is where the crankshaft flywheel is located.

    If your dealer's tech replaced the ignition coil nearest to the driver's side, then s/he replaced the coil for cylinder #4.

    Regarding the cowl area that needs to be sealed if water is seeping from the cowl onto the engine valve cover, this would be the seam between the two black plastic cowl pieces, at the center of the cowl. Just apply a small bead of black urethane sealant on the seam.
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  18. oleknz

    oleknz New Member

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    I have finally had it fixed. Went to the Dealership and insisted on being present when the ignition coils are replaced or switched around. I previously had the Coil #1 diagnosed to be bad - and apparently replaced. When I checked later on the new ignition coil was mounted on cylinder #4. (Mechanic claims he had been switching them around to confirm which one had been misfiring and just left it like that)
    The misfiring problem re-occurred soon after and the second diagnostic I ran on my own again showed misfire on #1 and on #2.
    I went to the dealership and the mechanic confirmed it in front of me.

    It took some argument for them to allow me to be there in the shop. I just told them: either throw me out and give me my money back for the unsuccessful repair or let me watch what you are actually doing. Screw the company's policies!

    The mechanic demonstrated to me that there was water in the spark plug well and some rust stains (did not mention that before and it must have been there before since the car was not washed and it didn't rain since then). So the water must be the primary reason for the misfiring as indicated in previous posts here.

    After replacing any misfiring coils and spark plugs i asked them to test the windshield cowl for water leakage. we pulled the car outside, hosed the windshield with the hood closed. Then opened the hood and indeed water seeps in and drops directly on to the Ignition coil #4. It looks that if you do a longer car wash, or there is some especially rainy day, water can easily reach all the ignition coils.

    So I am on to sealing the windshield cowl per bulletin EG063-05 and hopefully that would be the end of this chapter for now. My warranty is long expired so I will just do it myself since the dealership mechanic is not familiar with this problem and I am broke.

    And a side note: I argued with the sales rep why replacing the cabin air filter costs $90. Answer: "Well, all dealerships charge like that. It's actually very inexpensive. The part is $32/something and when you open the glove compartment it may brake or something :eek: - and we have to take responsibility for that..:("
    wow!

    thanks everyone!. All Prius Chat members, you rock! Stick it to the Man!
  19. tf4624

    tf4624 Member

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    Just to let everyone know who reads this, you can remove 4 of the coils in less then 5 min and replace them just as quick. if you do spark plugs add another 5 for gapping and tightening to specs You don't have to take off wipper coul just take black box off and boom you have acces.. ratchet away and your good to go

    but simple

    look at this

    Toyota charges 114-132 just for the part
    Labor for install is 114-136

    If you do it Labor=0 money
    Parts-80-105 per coil
    You can go to local pep boys or so 80-105 for coil and take 5-10 min to remove it.
  20. andyprius

    andyprius Senior Member

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    Great Job, Fighting for your rights:cheer2: