These common maintenance issues have been vexing driver... These common maintenance issues have been vexing drivers for years (U.S. National Archives, Flickr)
Recently, CarMD Corp. conducted a study and compiled the findings into what they called their Vehicle Health Index. CarMD is a device that plugs into your vehicle and then downloads vehicle repair data, letting you know what's wrong with your car. Among the findings of the study were the top five most common repairs you can avoid through proper maintenance.

1. Engine Misfire

Each spark-plug on your car is electrically timed to fire at precise timing to deliver power from the engine. If the spark fires at the incorrect time or not at all, it is considered a misfire. Misfiring of a cylinder can happen for numerous reasons. Here are the most common causes and related costs of the misfire condition:

• Carbon or oil fouled sparkplugs: $100 to $300 depending on cost of plugs and labor to replace. (Bear in mind that oil of carbon fouled plugs are the result of a deeper problem with the engine and to get to the bottom of such case will cost more time and money to fix).

• Bad spark-plug wires: $100 to $300 depending on cost of parts and labor to replace.

• Bad fuel delivery: $100 to $1000 depending on cause of fuel delivery problem: bad injectors, cracked intake plenum, new injector driver or flash programming of ECM (Engine Control Module) needed.

• Vacuum leak: $100 to $1000 depending on cause of vacuum leak.

• Mechanical breakdown: Broken valve spring, burnt valve, broken or burned piston or piston ring, blown cylinder head gasket. Repairs for this can run from $500 -- $10,000.

What to do? The best way to avoid an engine misfire condition is through following the scheduled maintenance in your manual. Keep your vehicle's engine tuned according to factory specs. Plus, a yearly trouble-code scan by a well-equipped shop will uncover any potential problems before they become major faults.

2. Evaporative Emissions Leak and/or Failure

The evaporative emissions system control (EVAP) system is designed to trap gas tank fumes. The system consists of the fuel tank, vapor lines, liquid vapor separator to prevent liquid gasoline from entering the system and the EVAP Canister, which has a purge valve on it. Fumes are trapped inside the canister, which is full of activated carbon. At certain times during engine operation, the canister purge valve opens up letting fresh air into the canister. This in turn forces the trapped gas fumes back into the engine's air intake and thus burned inside the engine.

Should the system develop a leak as a result of corrosion eating the lines or a compromised canister, the system will throw an "EVAP Leak" code in the computer. To fix the problem, one has to find the leak, or faulty component, fix or replace it, and reset the system. The whole process of diagnosis and repair typically runs anywhere from $100 to $700 depending on what's needed.

What do do? To keep EVAP Systems operation properly, always make sure you tightly re-install your gas cap after refueling. In addition, a good rust protection application helps to keep system line corrosion to a minimum. Always tend to lit check engine lights. If you let them go, an EVAP System problem can expand into major repair costs.

3. System Running Too Lean

If a "System Too Lean" code comes up, it's usually due to a vacuum leak, faulty injector driver, bad injector or a software update needed. The performance computer monitors engine operating elements such as coolant and air intake temperatures, amount of airflow into the engine, throttle position, etc. If the problem-code pops up, it's because one of these areas is compromised. The mechanic must scan the system, identify where the malfunction exists and repair it. Typical causes of lean conditions range from a bad vacuum line, faulty sensor, broken engine gasket to a cracked cylinder head, faulty intake plenum, warped throttle body, and too much more to mention here.

Repairs run anywhere from $150 and up because it can be as simple as a sensor replacement or wiring repair, but it could also be a major engine repair costing thousands.

What To Do? Regular maintenance and upkeep will avert these type of problems. Always tend to a lit check engine light because we don't want a small problem to snowball. Don't be penny wise and pound foolish when it comes to preventive maintenance.

4. Catalytic Converter Failure

Catalytic Converters fail for two reasons: either because of a leak from rust and corrosion setting in, or internal plugging from excessive carbon buildup or collapsed baffle or catalyst. The catalytic converter is a device that burns up any unburned gas in the engine exhaust, cleaning the tailpipe emissions. Problems crop up when more unburned gas is fed into the catalytic than it can process. For lack of a better term, the catalytic becomes "constipated" or clogged as a result of too much gas being fed into it. The clog takes the form of a "rock" of carbon that forms inside the cat, causing a restriction of exhaust gas flow.

The only way to restore the system to proper operation is to replace the catalytic converter. Now this is where most people stop the repair process. But then the new catalytic comes up with the same problem just a few months later. Why? Because the tech did not get to the bottom of the problem the first time. The reason the catalytic clogged was probably because there was uncontrolled fuel delivery. Make sure your mechanic gets to the root cause of the unchecked fuel delivery before paying the bill and driving away.

What to do? To avoid catalytic converter problems, keep the your engine up to snuff with regular scheduled maintenance tune-ups and system maintenance as per factory recommendations in your manual. It's really the only way to prevent premature failure of the system.

5. Exhaust Gas Recirculation (EGR) System Failure

EGR stands for Exhaust Gas Recirculation. This is an emissions system designed to lower combustion chamber temperatures in order to lower formation of NOx (Oxides of Nitrogen) gas, which contributes to harmful air pollutants.

Because of the system's very nature (feeding exhaust gas), it is highly susceptible to carbon (unburned gas) buildup, plus electronic control problems. EGR Valve complications arise from wear of the valve over time. Typical repairs include valve replacement, sensor or controller replacement, or wiring repair.

Repairs can run anywhere from $200 for an EGR tube replacement, to a valve replacement, while EGR passage cleaning costs about $700. Repair costs vary by year, make and model.

What to do? To keep your EGR system functioning properly, have a professional fuel system cleaning done every 30K miles. This will keep carbon buildup, the EGR systems greatest enemy, at bay. Attend to any check engine lights immediately.


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    • 1 Second Ago
  • 90 Comments
      defensearms
      • 2 Years Ago
      buy a Toyota next time!
      • 2 Years Ago
      nice article but you failed to mention the most common cause of engine misfire,carbon build up on the back of the valves and valve seat.this problem is exacerbated by a direct injection type fuel sys and the poor quality fuel available.every car today needs a periodic cleaning to prevent this type of problem.bg products which most manufacturers shun because they dont want to sell aftermarket additives.and no,i dont work for bg i just know what works from years of experience. to me this a big problem facing anyone that has a newer car.problems start as early as 10k miles and are often blamed on the car when in fact it is a fuel problem, AAA actually had a lawsuit against the EPA to reduce the amount of ethanol in fuel which is slated to rise from 10 to 15 percent,this ethanol is a contributing factor to carbon deposits and now its concentration is rising by 50 percent? these facts are known by everyone in the petroleum industry but are swept under the rug because guess who is subsidizing ethanol production.
      dt2k05
      • 2 Years Ago
      This was a good article. The one thing people are failing to understand in this business is that the diagnosis of the failure is the most important thing for a positive automotive experience. We charge $99 for diagnostic service (check engine scan, driveability or no start conditions). Professionals realize that the software, the equipment and the time you put into problem solving is involved. Meanwhile, customers have their crank no start vehicles towed into our shops and advise us that it's the fuel pump. We diagnose it and add 3 gallons of gas and the car seems to start and run well. Our repair recommendation from our diagnostic cost the customer 1/12 of what they diagnosed to be the problem. So is diagnostic work expensive? Before you answer that would you rather have someone guess at the remedy or know the cause and correction by completing a proper diagnosis? How about if doctors guessed at tumors, cancer, diseases because of what you sound like? Think an MRI, scan or blood test should be done or should we keep the diagnostic cost down and just remove the urinary bladder on a guess or an because of an Internet blog? Automotive has a bad reputation because cars rapidly and the training is driving cost of repairs up. It is not unethical to charge a price you deem fair for your expertise. If you suck at diagnosis, I would charge $50 for a scan or do what Autozone does for free. It is not helpful for you to have your car diagnosed by a parts sales person or cashier. This is why a CNA does not perform surgeries in hospitals either.
      • 2 Years Ago
      I am a female shop owner who despises nothing more than horror stories of women being taken advantage of at quick lubes and tire centers by fear tactics and high pressure sales gimmicks. We operate an "open" shop where customer are invited to come outside to discuss needed repairs so that they better understand what is needed. Because of these "pile it on" shops it makes it more difficult for the rest of us to effectively do our jobs. Customers who have been taken advantage of are naturally more skeptical and suspicious. We have found that helping customers to prioritize their repair to do lists or better yet to go over recommended services and repairs from a high pressure sales job will ease their apprehension and allow them to see through the hype. With patience and knowledge you can find an independant repair shop that really cares and wants your repeat business. Best place to start is to ask a friend or family member!
      GERRY
      • 2 Years Ago
      THE MOST HONEST MECHANIC IS MYSELF. IF SOMETHING BREAKS, I FIGURE OUT WHAT THE PROBLEM IS MYSELF. I AM NOT A PROFESSIONAL MECHANIC. IF I CAN'T FIGURE OUT WHAT THE PROBLEM IS, I ASK AROUND AND SOMEONE USUALLY KNOWS AND TELLS ME HOW TO DO IT. I HATE PAYING MECHANICS!!
        alc
        • 2 Years Ago
        @GERRY
        you go, must work at mc donalds
      • 2 Years Ago
      where and how do I get professional fuelcleaning and the costs.
      Buck
      • 2 Years Ago
      I been reading these automotive post for some time and never write in because I just don't. But I need to sure things up because all repair shops are not evil. I own a small auto repair shop / welding shop and also build nascar racecars, I take regular ASE courses to stay up to date. I work alone, can't trust employees to do the work right when your name is on it, been there done that. I spend a lot of money on equipment and computer diagnostic equipment. Snap on Verus, tire pressure monitoring computer to name a few. I use Alldata online diagnostic program. I work on domestic, foriegn, asian, imports, etc. I have hundreds of thousand dollars worth of equipment, friends and family say I'm crazy but I love what I do. 15 hour work days are common for me. I don't rip people off, Matter of fact I encourage people to hang around and see the work performed and explain how the part or parts work and what the problem is right in front of them. I don't hide the vehicles out back and run in with a clip board and bs people. I do a lot of things for my customers with out charging, I shoulden't but I do what it takes to make sure there up and running, that goes along way. I get referalls every day from customers, do you see where this is going. Greed will make you rich for a short time. I been in the business 35 years and owned my business for 20 years. I worked for a dealership and seen from the inside how they work thats when I decided I didn't want any part of that. I hate people writing in and saying all garages are rip offs. Yes I agree I seen many in my town come and go over the years, but I stay really busy. So what I'm getting at is look for the small shop with good credentials and work ethics, and down to earth willing to listen to what your saying. Most of all get involved when they show you something so you have a better understanding. Ask around town about certain shops, If they are respectable they will have lots of customers and you surely will run into one of them. Remember a good shop will have a lot of equipment to pay for and try to make a living like you. It cost a lot of money to properly repair something. Untill you been on this side you won't know what I mean. I hope this helps the public get a better understanding about this industry. Have a great day. Buck
      Brian
      • 3 Years Ago
      No one wants to spend any money on maintenance unless they have to. Well my co-worker found out the hard way. He never changed the timming belt at 60k. So at 76k. the belt broke on the free way ( 5pm on a friday)..The time wasted for a tow truck,The dealer said out of warranty ( remember at 60k.), the rent-a-car and the cost around $3,500. The cost of the labor/parts for a new belt $395. and the kit came with a new water pump.I ask him why he did not spend the money for a new belt.He told me he wanted a new TV..Go figure.
        • 3 Years Ago
        @Brian
        He got lucky. Most cars use interference engines, where the timing belt synchronizes action between valves and pistons, ensuring that the two are never at the same place, at the same time. If the belt rips valves remain in place, while the pistons briefly continue moving up and down, often bending or even shattering the valves.
        Bret
        • 3 Years Ago
        @Brian
        Buy a car that has a timing chain. Problem solved.
          David
          • 2 Years Ago
          @Bret
          Bret, Timing chains break too. Been there, done that many times.
          mrobin1863
          • 2 Years Ago
          @Bret
          I agree. Been in the business many years and the only timing chain I've seen break was on vehicles that should have been put down long before. Timing belts are a cheap, ineffective way to time an engine for a customer who wants long term service.
          Aspclgntt
          • 2 Years Ago
          @Bret
          Timing belts are a way to make an engine cheaper, they are desined to last a fraction of time as a chain. Its a cheep shot from the manufactures.
      jaybeach8
      • 2 Years Ago
      I can't believe the outrageous cost quotes: $300 to replace sparkplugs? Is the author paid by garage mechanics to write this stuff? $300 to replace plug wires? $1,000 to fix a vacuum problem? Please stop putting this garbage on your site. It's almost as bad as the outright lies and misinformation you print about gun owners.
      Vin Diesel
      • 1 Year Ago
      i tried http://www.injectorshop.co.uk thanks anyway
      wc98
      • 2 Years Ago
      5 most common repairs all caused by THE most common problem: owner neglect
      Cas
      • 2 Years Ago
      Buy a Horse.
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