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Learning, Sharing, and Teaching => Ask a Mustachian => Topic started by: cincystache on February 21, 2020, 12:55:49 PM

Title: Honda Minivan Troubles (Fix or Replace?)
Post by: cincystache on February 21, 2020, 12:55:49 PM
Hi All,

We are a one car family with a 2010 honda odyssey EX-L with 120k miles on it. We bought it used for 8500 cash last May. I put an additional $3,000 in maintenance/repairs to get it in good shape.

Here is my problem.

5 months ago the check engine light started flashing on the highway and the engine was misfiring, we limped into our destination and my brother suggested changing the spark plugs which we did (all 6 with OEM plugs). The problem went away, no lights or errors.

3 days ago my wife was driving the kids on the highway and out of nowhere, same issue. Check engine light is flashing, misfiring at low speeds and idling poorly. She drove it home right away and when I restarted the engine 5 minutes later to drive it to the mechanic there was no engine light and no misfiring. Very strange.

I took it to our local mechanic (not honda dealer but reputable local shop) he can't seem to figure out any obvious errors other than some low voltage readings on a few sensors but nothing he would suspect would cause the issue. He suggested changing the ignition coils but isn't confident that will fix it. Two of the coils are aftermarket already suggesting there might have been an issue in the past (?)

So here is my question. What should we do seeing as this is our only car and we want something dependable?

1. Listen to our mechanic and replace all ignition coils with new OEM parts ($600) and hope for the best, not knowing if this will fix the problem long term.

2. Take the car to a honda dealer for a second opinion and possibly learn of a new fix?

3. Sell the car and get something else with the proceeds.

4. Other? anyone ever have a similar issue on an odyssey?

If the mechanic was confident the coils would fix the issue I wouldn't hesitate to do that but I'm worried I'm just pouring money into something that isn't worth it. I was under the assumption odyssey's could easily get to 200k with relatively minor mechanic issues.

Thanks for your input, let me know if you need any other information, I'll try to respond quickly.

Title: Re: Honda Minivan Troubles (Fix or Replace?)
Post by: chemistk on February 21, 2020, 01:10:46 PM

I think I know exactly what's going up. Look around for "Honda Odyssey VCM Misfire". I would just probably forget about the coils for now.

Basically, your van, my van (a 2014 EXL), and most other Hondas with SOHC V6 engines manufactured in the last 15 years has an active cylinder deactivation function called 'VCM'. Whenever you see the 'Eco' light on your dashboard, between 2 and 4 cylinders have been 'deactivated' (no fuel or spark to that cylinder) to improve fuel economy. Sounds nice, right? Well, it's not so nice - Honda (well actually, most manufacturers) did not implement it very well and for a number of reasons that forums/Google can go deeper into, the two cylinders most frequently deactivated can become fouled with oil & carbon buildup and/or a host of other problems.

The most common issues that occur are 1) misfires because the spark plugs are fouled and 2) bad vibrations when gears change or the engine starts because the active engine mounts have been damaged by the various cylinders coming on and off.

I would take your van to a reputable Honda mechanic (not dealer) and explain the issue. I can't tell you what the fix will be, because it all depends on how bad the VCM treated your engine. Many owners go a whole lifetime of the van and never have issues. Others have tons.

You SHOULD seek a fix, though. If you can get past this, are changing the transmission fluid every 15k miles, and know that the timing belt service was done at 105k miles, your van will absolutely last to 200k.

If you're interested in preventing the VCM in the future, research Honda VCM Muzzlers.

Good Luck!
Title: Re: Honda Minivan Troubles (Fix or Replace?)
Post by: Xlar on February 21, 2020, 01:21:42 PM
I would start by purchasing an OBDII scanner that works with your phone. Then when the check engine light appears you can read the code and diagnose the actual problem. I'd advise against throwing parts at the car and hoping it solves the problem...

I would definitely keep the van, I know several people that have way more than 120k miles on their Honda Odyssey's without significant issues. So if you get this problem fixed you should be good to go for many years.

If you have an android phone I'd recommend the Torque app with this scanner: (

If you have an IOS phone I'd recommend the Dash Command app (Sadly no free app available) with this scanner: (

If you get a scanner and read the code post it here and we can give you advice or make an account on one of the Honda Odyssey forums ( ( and they will give you advice. Or take the code to your mechanic. Knowing the code will then show what specific diagnostic steps should be followed to diagnose the specific part that has failed/is in the process of failing.
Title: Re: Honda Minivan Troubles (Fix or Replace?)
Post by: lutorm on February 21, 2020, 03:30:50 PM
I've heard a saying in aviation: "it's not the mechanic's job to diagnose the problem, it's his job to repair". The idea is that it's almost impossible to figure out what's wrong with the plane in the shop instead of flying, so it's your job as a pilot to gather as much data as humanly possible about what is happening, when, what causes it, etc. Especially so if the problem is intermittent.

This doesn't exactly cross over into road vehicles, because the mechanic can more easily go for a test drive, but in the context of intermittent problems I believe it applies exactly. If you take a car in and say "the car did this funny thing but now it's fine" there is close to zero chance of them correctly figuring out what happened and fix it. They can guess, and fault codes can give some hints, but you really don't want to start replacing parts based on guesses because that will be expensive and likely won't fix it unless they've seen the exact same thing several times in the past.

This is frustrating for the owner, of course, but with an intermittent problem I think the answer is almost always to continue driving while noting everything you can about the problem, unless it's a totally unsafe thing.
Title: Re: Honda Minivan Troubles (Fix or Replace?)
Post by: cincystache on February 21, 2020, 03:55:24 PM
Thank you all for your quick replies.

@chemistk : I spoke with my mechanic about the VCM misfire and while he agreed that could be the culprit, the solution isn't clear. I appreciate the heads up though, I had no idea there was a known issue with these engines.

@Xlar  Thanks for the advice, I'll look into those scanners and if/when the issue comes up again I'll post it to this forum.

@lutorm : great analogy. Your advice was pretty much exactly what my mechanic recommended at the end of today "Keep driving it and call us when it happens again or starts happening more frequently". It is frustrating but it's probably the right thing to do in this situation. I don't that it is completely unsafe other than it feels like it is going to stall when we are at low speeds but never actually has (only happened twice so far).

I think we are going to hang on to the van and try to get the most life out of it and until we have a fix in place we will borrow/rent a different van for a long road trip maybe 1X per year just to avoid it leaving us stranded far from home.