2012 Camry SE Misfiring

I bought my 2012 Camry, with 12,000 miles from the Dealership in December of 2013. The car was sold as CPO, car was purchased on Dec 30… just 6 weeks ago and I have had numerous issues with the car Misfiring. When I arrived at the dealer, the CHECK ENGINE and TIRE TRACTION lights are one and the car is running very rough as acknowledged by the service techs. For the 2nd time now, I am told they are not able to recreate the problem, so they are not able to fix it.

Does anyone have a suggestion? This is my 4th Toyota ( iam a fan), and I have NEVER had this many problems with a Toyota. Did I get a lemon? Sevice tech says he can’t fix it unless he knows exactly what’s wrong. I am asking him to check the spark plugs, check the ign coil…and his response is that they can’t just go on a wild goose chase, they need to know what they are looking for. Does this sound reasonable?

I appreciate any help you all can give me.

When the Check Engine light goes on, a code is set. Even if the code resolves itself, the code stays in memory to be pulled with a scan tool. Any codes found can lead the technicians to the problem. If codes are not found, there may be an ECU problem.

I don’t understand. The techs say the engine is definitely running very rough; yet they next say they cannot duplicate the problem? You must be leaving something out. Please explain.

As BK says above, this type of problem is best approached using the car’s built in diagnostic software to figure out what is going wrong. If the CEL is on, the techs should – and probably did – connect their Toyota scan tool to the diagnostic connector, and have a read out of what the problems the car’s software is reporting. Ask the techs for a copy of that report, then tell us here what it says.

The techs are correct to not just start replacing stuff at random. While it could work in the 1960’s and 70’s, usually little progress is made using that technique these days, what w/the complexity of computerized modern cars. But they should be able to tell you what the car’s software is saying is wrong. If they push back, tell them you paid for that software when you purchased the car, so tell the techs you should be shown the content of what the your software is saying.

They are not very good techs are they? If the check engine light and traction control lights are on, then there are specific procedures for narrowing down to the root cause, all they have to do is follow those procedures. Mention lemon law next time you go in.

A car that is traded in in one year with only 12k miles on it has had something seriously go wrong with it. It may have been turned in under the lemon law once already.

Sometimes new cars are loaned out to employees of the dealership or the manufacturer for a year to drive. Give the employees a chance to see the plusses and minuses of the car, so they can address customer questions. Then, after the cars are a year old, they are sold by the dealership as dealer-returns, program cars, or some such nomenclature like that. Maybe this is one of those cars. If so, that wouldn’t imply there was something known to be wrong with the car. I suspect there is just some part that has gone bad, needs to be replaced, and the only question left to determine is: which one?

How many miles on the Camry?


speak with the service manager and request that the most experienced and/or smartest mechanic diagnose and repair your car

Also tell him you’ll leave your car until it’s repaired

Tell him “Don’t bother calling until it’s repaired.”


That gives the dealer the authority to park the vehicle out on a back lot for who knows how long? While the owner still makes the car and insurance payments.



It would be frustrating if the dealer tells the customer “Come pick up your car because we are unable to figure it out, in spite of the fact that it’s running like crap”

Of course, they’ll word it a little differently

My old service manager always told us to never give up. The customer has better things to do than make up stories about check engine lights and rough running. They’d rather be somewhere else.
In almost every case, dogged determination paid off and we duplicated, diagnosed and repaired the problem

It would be interesting to know what kind of diagnostics were done and how far that process went.

Just noting that some performance issues will not set a code and there’s always the possibility that misfiring could just mean generally poor performance instead of a dead cylinder.
If that poor performance is related to contaminated fuel then it’s not a warranty issue at all. Telling a customer they may have to pay up on something like that does not always go over real well on a car they recently purchased.

Change the plugs. Design is COP? Put new coils on. Good start. It’s warranty stuff, right?

Warranty won’t let the dealer mechanic use the shotgun approach to diagnose/fix the car

There have been very little diagonostics done that I can tell. When I arrived to the dealer, everyone acknowledged that the car was running poorly and the engine lights were on warning. I was told that CYLINDER 2 is misfireing, but because when they were ready to work on it, it was not making the same misfire, they could not fix it. When I get the actual code# I will post it here, if that helps.

The car just turned to 13,000 miles…so very few miles.

Offhand, sounds like a code PO302 was involved as that would mean a specific cylinder misfire on that cylinder.

There are a number of reasons why that misfire could occur. Spark plug, coil, fuel injector, wire harness or PCM fault in the coil or injector wiring, moisture in a spark plug well, or low compression.

Does this problem seem to surface when the engine is warmed up and not when cold?
Has there been any weather conditions involving heavy fog or very damp conditions?

The reason for the first question would involve a theory that valve lash is tight on that cylinder and becomes too tight when the valve train is warmed up to operating temperatures; leading to a valve not seating which would then cause lowered compression and a misfire.

@Camry_Gal, just FYI to keep yourself informed - in order for each cylinder to “fire” correctly it needs to take in fuel (from fuel injector) and air (from air intake), it needs to compress them (engine compression), and then the spark has to show up at the right time to blow up the fuel/air mix. If anything in there goes wrong it will miss-fire.

The typical place to start for diagnosing a misfire is spark. It’s normally the cheapest and easiest thing to check. The problem the dealership had with helping you is half-way legit - but only half way. If it isn’t acting up for them, then they could do X, Y, or Z but not be able to verify that they actually fixed it. That’s the legit half. The other half is that someone should have at least pulled the # 2 spark plug and coil and inspected them for any obvious signs of an issue. So IMO you are correct, and they are beinf twits.

Since it is confined to the #2 cylinder, you are most likely looking at an issue w/ plug or coil, or some issue with that fuel injector. Compression problems are always a possibility but would be very rare on an engine this young. This includes the only kind of “air” problem that you’d see show up on only one cylinder - an intake valve issue. So there is no wild goose chase that would go on with this. The range of possibilities is small. I hate the blank stare and shrug from a shop. It just means “we can’t be bothered with your problem”

The problem surfaces intermintly, the last episode the misfire happened after driving for about 5 or 10 minutes, in town. The previous incident began misfireing within minutes of starting the car and got progressvly worse. I stopped, pulled over a few times and shut the car down, and restarted the car as the service tech on the phone suggested. The dealership also asked me if it was raining heavily. I believe it was drizzly that day, but clear skies at other times.

If there are no codes being set or any obvious fault present then this goes back to what db4690 stated; warranty will not pay for a fishing expedition.
A mechanic can go fishing all day long for free.

I fully agree that compression issues should not exist on a 2013 model car with only 13k miles. However, it’s a production line item and faults can and do occur with anything rolling off of an assembly line.

We had a Subaru into the shop once with tight valves and both heads so severely damaged that neither head was repairable. That car was less than a year old and had 7k (not a typo) miles on it.

Diagnosing misfires on a single cylinder isn’t easy, and usually involves switching components around, and seeing if the misfire goes with them. For example, if you switch the number 2 and 4 coil, and the misfire goes to the number 4 cylinder, you know the coil is the problem. Injectors, coils, spark plugs, etc can all be switched. Usually a mechanic would start with shifting the coils. Ask if the dealer shop will shift the coils around even though the problem isn’t happening at the time. Then you could drive the car, when it acts up again, take it back in, they can see if the code has changed to another cylinder. Here’s an article on how this is typically done.


I know that the discussion on this new 2012 Toyota Camry misfire was back in 2014, but I have the exact same issue on Cylinder #2. I have had the iginition coils replaced with the sparkplugs by a mechanic then myself 3 times over the last two years. Probably only driven 60,000 miles over the last two years. Had used cheap Chinese mfg ignition coils bought on line. Each time it seemed to fix issue, but each time the problem came back sooner each time, I.e. 10 months later, then about 7-8 months, now about 6 months. Recently went back to the original Denso coils and sparkplugs to see if that takes care of it long term. But still can get a small rough vibration 35-50 mph range. I have to give a little more gas to get rid of misfire. My gas mileage from two years ago went from about 32 mpg to about 30 to more recently 28 mpg.

Toyota dealership said to try ignition cleaner because of ethanol type gas that is sold today. Tried that, esp. the Gumout brand specified for ethanol gas. I bought the per tank one and the one time per year one. Seemed like car ran better until I refilled with new gas. Started using non ethanol based gas. Thinking about going to higher octane gas.

Toyota then said that it might be the Throttle Body Assembly. About $1500 repair. Part alone and $6.00 gasket is about $966.00. I asked if there was a separate Throttle Position Sensor. They can’t find so it is all built in to the whole Throttle Body Assembly…ouch!

Going to clean the Throttle Body interior first and Mass Air Flow wire.

Then I guess I will go to fuel injector. Any suggestions or remedies next? Unless the misfires get to the point the car won’t run smoothly, the trouble warning lights don’t come on. There are no light coming on now even though it is starting the very beginnings of what have happened before, but a lot sooner.


The throttle body and the MAF sensor affect all cylinders pretty much equally. Since your problem is causing a misfire on #2 only, I’d dismiss those two things. You have a coil on plug type of ignition. That limits you to things that only affect the #2 cylinder.

The easiest thing to do is swap the #2 coil with any other coil and see if the issues move. Next, replace all the spark plugs unless that has been recently done or the problem came up right after the plugs were changed. If it came up right after the plug change, then just change that one plug.

Check the pins in the connector to the coil of the affected cylinder just in case one of them got damaged. I’d also put a little dielectric grease on the contact between the coil and plug.

Next would be a compression check. Even if it is good, I’d remove the valve cover (get a valve cover gasket kit) and check the valve lash.

After all this, then check each injector with a noid light or listen for the click with a stethoscope. Then I’d look at swapping the #2 injector with another one to see if the problem moves.

Somewhere in all this, the problem should be solved. If it isn’t, then check the wires between the PCM and the coils. After all that, it could be inside the PCM, not what you want to find out.