Will driving my car with this error message damage my car?
August 28, 2016 9:40 AM   Subscribe

Car is a 2009 Toyota Matrix with 67,000 miles. Check Engine light came on two days ago, went off after oil change, came on again. Diagnostic at auto store today said P0354 Ignition Coil D Primary / Secondary Circuit. Light went off again after restarting after diagnostic, but I've only drive 5 miles since. It will difficult to get car to shop this week; might put another 50 miles on the car in the meantime. Is this just a performance issue, or might I damage the engine by driving with this issue? Thanks.
posted by Jackson to Travel & Transportation (7 answers total) 2 users marked this as a favorite
Best answer: It sounds like you have an intermittent fault with the coil on your #4 cylinder. The issue is not so much damage to the engine as damage to the catalytic converter due to unburnt fuel. Some cars will shut off injection to a cylinder with a malfunctioning coil, but I don't know if your car does.

That said, if the issue is intermittent and there are no other symptoms (e.g. rough running), then you should be able to drive for 50mi. I'd avoid driving if possible if the light comes back on. You could also physically check the wire going to the #4 cylinder to make sure it isn't the problem.
posted by ssg at 9:53 AM on August 28, 2016

Best answer: I don't think there is too much risk in 50 miles. Yes, if you have a slight misfire you may do damage to the catalytic converter (because the fuel in the affected cylinder is not completely burnt), but if you don't feel any loss of power or rough running, then this may well be the very beginning of a fault rather than a major problem.

If it were me, I'd book it in for the work as soon as was convenient. It's not 'drop everything and take it to the shop' urgent, but it is 'don't drive it more than is necessary'. There is a slight chance that the misfire may get worse in that 50 miles, which means much more likely damage to the catalytic converter, or some chance of a roadside breakdown, but I think you'll be safe with 50 miles.
posted by Brockles at 10:03 AM on August 28, 2016 [1 favorite]

Response by poster: Very helpful, thank you ssg and Brockles.
posted by Jackson at 2:46 PM on August 28, 2016

Best answer: If was an urgent issue, the CEL would be flashing.

posted by intermod at 9:38 PM on August 28, 2016 [1 favorite]

Response by poster: Intermod, good information. Jeez, how could I not have checked Wikipedia. Thanks.
posted by Jackson at 4:14 AM on August 29, 2016

I had an ignition coil go out on my 2003 Toyota Corolla and replaced it myself. Took less than half an hour. If you're handy it's just a handful of easy screws/bolts and a $80 part. The auto store should be able to help you determine which coil you need, but it's something like this.
posted by gregr at 7:08 AM on August 29, 2016

If was an urgent issue, the CEL would be flashing.

This speaks to why I hate the CEL so much. It gives so little information while portraying itself as a simple yes/no/hell no indicator. If the CEL is just on, there still may be something happening that is damaging part of your car (the Catalytic converter in this case). A misfiring cylinder is not always a flashing CEL fault but any unburnt fuel down the exhaust can damage the catalyst. Usually if the CEL is flashing, it is not just 'urgent' but can be 'imminent catastrophic failure' (ie low oil pressure, overheating or something equally bad). That wikipedia article is a little misleading. The 'Trouble' section mentioned has been largely replaced by the CEL blinking. Blinking is REALLY bad and means pull over and have it checked (do not pass go, do not collect $200 etc). But the CEL being on can mean a host of things of varying complication, some of which will cause further damage (usually cost related) if you ignore it, some of the time it is absolutely nothing of issue (ie gas cap not tight).

It's a terrible, terrible system, basically.
posted by Brockles at 10:07 AM on August 29, 2016

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