Check engine light on? Pay attention

th-1If money is piling up in your checking account, here’s one way to divest yourself of the burden: Ignore both the manufacturer’s suggested maintenance tips and the “check engine” light.

According to CarMD.com, a faulty oxygen sensor is the most common reason for that check-engine light to pop up on the dashboard. The fix could be as simple as changing out a dirty air filter, but you could also be on the hook for a $259.30 (on average) sensor replacement.

Some folks push the envelope on maintenance visits or ignore the manufacturer guidelines entirely. They think that’s frugal, but it isn’t.

The oxygen sensor is a good example. Sure, you’ll save almost $260 by not fixing it. But you’ll pay for it in other ways. Expensive ways.


A bum oxygen sensor can affect gas mileage by as much as 40 percent, cause vehicle misfiring and ultimately force you to replace the catalytic converter ($1,157.27).

Vehicle make/age, parts availability and price, and auto shop labor rates all contribute to the high cost of maintaining Old Faithful. We can’t control that.

“However, something everyone can control is how quickly they address check engine light issues when they arise,” says David Rich, CarMD’s technical director.


The reasons behind the light

A few other common reasons for the check-engine light to illuminate are:

Tighten or replace fuel cap: Often it’s just a question of making sure the cap is replaced correctly. Easy enough.

Replace catalytic converter. As noted above, this is not a cheap fix. However, the converter doesn’t usually fail unless a related issue – oxygen sensor, spark plugs – gets ignored consistently. Again: When the car sends up its version of the Bat Signal, pay attention.

Replace spark plug(s) and wire(s). This is not a quick-and-cheap fix, either; the average cost is $361.56. But if you ignore this issue you might wind up with catalytic converter and/or ignition coil problems. (Ka-ching! go the strings of your repair person’s heart.)

Replace mass air flow sensor. This auto part measures incoming air and determines how much fuel to inject. It costs a little over $400 to fix, but fuel economy can drop by as much as 25 percent if this sensor goes bad. Given the once-more-rising cost of gasoline, this is not a repair you can afford to ignore.

The analysis was based on nearly 100,000 repairs done last year on automobiles built from 1996 to 2014. It noted that the five most expensive places to get repairs were the District of Columbia, Delaware, New Jersey, California and Connecticut. The most affordable states were Wyoming, Montana, Nebraska, Michigan and Vermont.


Pay now or pay (lots more) later

The data suggest that the states where repairs cost the least (more on that below) has a higher percentage of simple repairs vs. major, days-in-the-shop ones. Rich says this indicates that drivers in those states “were likely more vigilant with addressing repair needs quickly.”

Rich also notes that consumers can shop around in their areas for qualified repair places and parts, since costs can vary widely.

The moral of the story is twofold:

Pay attention to that check engine light. Your car is crying out for help.

Pay attention to the manufacturer’s scheduled maintenance program. It costs money you may not feel you can spare right now. But you can pay now or overpay later, i.e., when you have to fix an issue you could have addressed early on. You know, when it was cheaper.

Readers: Do you follow scheduled maintenance?

Related reading:

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  1. I have never ignored the maintenance lights in my car, and I always make a trip to the dealership when I was living in the states. I really believe this has saved me lots of money over time.

  2. Tina in NJ

    My car manual calls for an oil change every 7,500 miles, but the little sticker only adds 3,000. Cute trick, guys, but I’m on to you.

  3. Aunt Leesie

    Years ago, on an older vehicle that was my DH’s, he let a small oil leak go. It eventually became a more significant leak that left a puddle in the driveway. Still he didn’t take it in. After two years of nagging, I finally took the car in, and the repair? A whopping $1200!!! When he let the squeaking brakes go too long, it was another big chunk-o-change to replace the damaged drums. Part of the problem was I didn’t want to have to deal with cars. This wasn’t MY car, either, but I learned it can be financially painful to be stubborn.

  4. Cathy in NJ

    I drive 100 miles roundtrip a day to and from work so I take my car very seriously. It always goes to the dealership for maintenance. When I bought the car, the deal was 0% loans on the car. I added the maintenance and got 0% on that as well. The car payments were higher but I had no maintenance worries for years. Being stuck on the side of the road in Jersey is a nightmare.

    • Donna Freedman

      As a NJ native, I have to say I agree about the “stuck on the side of the road” thing. In the part of Jersey where I grew up, that meant “stuck on the side of a back road.” At least today we have cell phones.
      Take care of your car and it will (usually) take care of you.

  5. My check engine light is on in my van. Den ran the codes and its an O2 sensor. Hmmmmmm, seems like the fates are trying to tell me something. I’m going to replace the gas cap first though, sometimes the light goes off for no reason. It’s always something. And something is usually expensive.

  6. Tina, The newer lubricants are made to go a little longer, but I still change my oil every 3,000 miles, on the advice of my mechanic. You can squeeze another 1,000 to 1500 miles out of an oil change, but to me, 7,500 miles is playing with fire. I have been diligent about changing the oil in our cars and making sure they get their scheduled maintenance, especially flushing and filling the cooling system every 2 years. It is a lot of money upfront, but it does save a lot of headaches down the road, pardon the pun. And yes, at one point I also had a 100-mile round-trip commute every day… I was getting the oil on my Dodge changed every 6 weeks! But it was worth it, because we got 186K reasonably trouble-free miles from that car. Got 184K out of the next one, an Olds, and now the Ford is up around 120K, and I think it’s because we take care of them.

    • Tina in NJ

      It was the mechanic (who has since moved to Vegas) who pointed it out to me that the oil should be changed every 7,500 miles according to the manual. This is synthetic oil that’s required and it costs $80, not $30. At the recommended interval, the cost is about even, so I’m pretty confidant going the 7,500 miles or so between oil changes. Trouble is, I don’t commute, I go months between oil changes

  7. I drive my car very little, and I’ve made it a point to have the oil changed every six months. That may only be 1200 miles further along than the last oil change, but I think it is better for the car to have regular service.

    My dealership usually has a “bulk pack” of oil changes that you can get where the final price per service is less than half of their normal charge (so it is along the lines of the cost of a “instant/drive up place” with a coupon.)

  8. Rachael

    My check engine light has been on for years. We have replaced every item the code reads (including 4 oxygen sensors) and we can’t get the check engine light to stay off for more than 20 miles. Several dealerships and shops also can’t get the light to turn off, so I think it has to be just a faulty light at this point.

  9. You mentioning ‘tighten or replace fuel cap’ reminds me of an issue I ran into on 2010 Ford Escape. Ford came out with this easy fuel system (http://owner.ford.com/how-tos/maintenance/fuel-supply-system/easy-fuel-capless-fuel-filler.html) where you don’t use gas caps. My check engine light kept popping on. I had it diagnosed twice & each time it came back to my gas area. No one knew how to help me. So I ended up buying a locking gas cap & voila.. it fixed the problem! Oh, AND I asked the dealership if they’d honor the MSRP listed on Ford’s website for the price of the part & they did! 😉

  10. My husband likes to ignore the check engine light! He says that it goes on and off, so for him, that means it’s not on – scares me as I’m pretty sure it’s going to bite him when he does get it checked! I also agree with those that change their oil more often than recommended. I figure we can’t go wrong with changing it too often, but the stakes are high when we delay.
    We must also remember to set aside money for car repairs – painful but necessary, right? Thanks for your blog – now I need to get my husband reading it too!

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