How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Toyotapro Your Own Question
Toyotapro, ASE master tech
Category: Toyota
Satisfied Customers: 9974
Experience:  ASE Certified, 10+ years Lexus and Toyota Certified
Type Your Toyota Question Here...
Toyotapro is online now
A new question is answered every 9 seconds

2002 Camry: check engine obvious misfire under load..P0301

Resolved Question:

My 2002 Camry's check engine light is on and flashing. The car has an obvious misfire under load. The diagnostic codes P0300, P0301-P0304, P0446 and P1300 were all present when I had them read. I replaced the plugs and by disconnecting the coil packs one-at-a-time determined that cylinder #2 was not firing. I replaced that coil pack - but the change had no effect. I understand that the 4 coil packs are controlled by 2 coils - each controlling two cylinders. Could the coil controlling coil packs 3 & 2 be bad? How can I test the ignition components to get to the root cause of my problems or could the problem be caused by a bad O2 sensor, crank sensor or some other non-ignition component? HELP!
Submitted: 8 years ago.
Category: Toyota
Expert:  Toyotapro replied 8 years ago.

Hello and thank you for using just answer.

Verify for me here- this is a 2002 4 cylinder correct? Are all these codes currently stored?

Customer: replied 8 years ago.
Hi Peter,
Sorry about that - yes this is a 4 cyl and yes all of the codes were stored when I had them read at autozone last night. (The check engine light has been on for a while)
Expert:  Toyotapro replied 8 years ago.

Thank you.

You have 2 issues here.

First let's seperate the codes.

P0446 is most likely why the light has been on for a while, this is a EVAP system leak, not a big deal right now or anything to be alarmed about, this is most likley just a bad fuel cap or loose line.

What you need to focus on is the p300 codes and p1300.

P1300 is an igniter circuit code. You are incorrect on your coil information.

Each cyliner has it's own coil pack bolted above the spoark plug, this contains the coil and igniter for each of the independant cylinders. Most likely you have 1 bad ignition coil here, to properly diagnose this you need a scn tool to read the data list to "see" what cylinder is misfiring. Do NOT waste your $$$ on a coil from anywhere other then the dealer, trust me on this one. Get 1 new coil and move it around if you don't have a scan tool to better trace this. I am about to drive home here but will be back online shortly if you need more input on this.

Customer: replied 8 years ago.
Hi Peter,
Thanks for the information - the "coil packs controlled by two coils" information was courtesy of the boys at Autozone last night - so it doesn't surprise me that it's wrong. As I mentioned earlier I had replaced the plugs (cheapest part) first. It was after that step when the problem still existed, that I used the process of elimination (outlined earlier) to identify the cylinder that was not firing. I purchased a brand new coil pack (90080-19023) from toyota and installed it on the suspect cylinder -still no change. (That was a quick $100!) So, what would keep a brand new coil pack from working? Where do the four wires connecting each of the coil packs originate? What signals or voltages do they carry? Again, is there something upstream in the ignition system that is causing the issue or is there some other sensor (Crank/Oxygen etc...) causing this problem. I'm a old school gearhead so some of this electronic/sensor controlled stuff is painful. Thanks
Expert:  Toyotapro replied 8 years ago.

Yes this can be a little confusing, each coil pack has 4 wires, a power, a ground, a igt and an igf signal, the power and ground energize the coil, igt and igf are the computer signals to fire and to tell the computer that the coil did fire. When igf does not send signal back it sets the p1300 code, you need an osciloscope to check these 2 signals.

Also be aware of a few more things here:

1- the catalytic converter is VERY sensitive on this car and very expensive, plan on a $800 part if you keep running this engine with a misfire

2- spark plugs- you need to be sure you used IRIDIUM spark plugs, required by this system

3- still needing a scan tool here, unplugging a coil is not the proper way to check for a misfire, you need to read the misfire data list to determine this.

I would take that new coil and move it around to each of the 4 cylinders to see if this clears it up if you have no scan tool access or install a spark tester to "see" spark.

Customer: replied 8 years ago.
Thanks. The new plugs are Autolite XP3923 Iridium plugs. (I've read some pretty negative threads about Autolite plugs in VTTI 4-cyl engines. Are those negative comments justified in your opinion? Should I go back to NGK IFR6A11 plugs? Also, I thought the P0300 code indicated random misfires and the P0301, P0302, P0303 and P0304 codes indicated that all four cylinders were affected. It sounds like we'll be headed to the Toyota dealership for a $98 diagnostic check followed by a serious repair bill. I'm just trying to separate a reasonable estimate/bill from the bill the dealer passes on to an uneducated consumer. Any other advice on how to keep the bill down?
Expert:  Toyotapro replied 8 years ago.

I have to be honest, yeah I'm laughing a little right now, yes autolite and Bosch are both horrible plugs for this motor, sounds like you got taken advantage of at autozone last night. I highly recommend only a NGK or a Denso spark plug in this car. However the spark plug will not cause a constant/heavy misfire as you have right now or the p1300 code.

Before you spend $100 on a diag fee have you checked to see what scan tools are available at auto zone? All you need is a scan tool that can read codes and data lists.....many parts stores also RENT scanners or high quality. I would like to guide you through this here to save you some $$$ but certain things will require some scan tool tests. My fear here is you start throwing parts at the car and not resolve anything or possibly damage a $800 converter.

We need to see a datalist for misfires at this point.

As long as you have compression then you will find that a coil or a fuel injector is the issue here.


Logging out for dinner, I'll be back shortly if you need me.

Thank you

Customer: replied 8 years ago.
Will disconnecting the battery - reset/clear the codes and data lists or does that have to be done with a scanner connected? I'm considering taking a run the parts store to look into scan tools and thought it would be great to clear the history and see what a new data list looks like after theXXXXXto the store.
Expert:  Toyotapro replied 8 years ago.

Yes disconnecting the battery will clear the memory in the ECM and reset the light, disconnect the battery for several minutes.


NO DO NOT DRIVE THE CAR! I guarantee a $800 catalytic converter failure and major issues if you do so. Stop driving this car. As I stated before my intention is to help you here and try to save you $$$$, if you drive this car you defeat the purpose and intentionally cause additional damage.

Toyotapro and 3 other Toyota Specialists are ready to help you
Customer: replied 8 years ago.
Message received and understood - I'm done working on this one, so we're off to the Toyota dealer tomorrow for diagnosis and repair. (Say a little prayer for us tonight.) Thanks for all of your time and advice.

I'll stick to working on my 68 Camaro. It's 400hp, 383 stroker, is sooo much easier to deal with! Thanks Again.
Expert:  Toyotapro replied 8 years ago.
I understand, (nice ride). Thank you for your time then, have a good evening and feel free to reply back if you need a second input after the dealer looks at it. I highly recomnmend having it TOWED in becuse of the running condition. Have a good evening.