Understanding "lemon" cars, how do they happen?

I’ve been watching a lot of YouTube automotive factory plant tours and also National Geographics Megafactories series. I’m learning a lot about how cars are made. This got me wondering about how some cars end up being “lemons.” How does it happen? Where does it happen? Which part of the car is most likely to cause a car to be declared a lemon?

My thinking is that the car is basically asssembled piece by piece and there are thousands of pieces, conceptually it might be like a bunch of lego blocks being supported on top and by the side of each other.

So, if an engine or transmission ends up being problematic, why wouldn’t replacing it solve the problem?

Each and every component can be replaced wholesale, right? Wouldn’t that fix the problem?

So, how does a lemon car happen? Isn’t everything fixable?

I suppose if the structure of the unibody is ‘defective’----that can’t easily be repaired and thus the car has to declared a lemon.

Please do chime in.

Do lemon cars even exist? Or, is it a legal or conceptual fiction?

A “lemon” is simply a car that after repeated attempts at repair simply cannot be made reliable. Yes, they exist. Occasionally a subassembly with be produced with an anomolie that causes an undiagnosable malfunction. Cars are a whole collection of systems created from a whole collection of things both complex and simple. The performance and/or dimensions of every single one varies from piece to piece and assembly to assembly. When this happens within the variation that is a fact of life for every repeated act, it’s called “normal variation”, but occasionally one parameter will stray from normal variation for any of a countless number of reasons and not be detected in the manufacturing process, causing a performance problem that can’t be traced to it. I’ve done a great deal of failure analysis in my years in the manufacturing industry, and it can be very complicated.

The “root cause” can be as simple as a worn tool, a worn machine, or a hungover machine operator, or as complex as a thermally induced stress fracture on the inside radii in a surface mounted piece of dielectric “chip” in a relief hole on an aluminum-oxide substrate that only becomes intermittent when heated. I actually had that one. The “root cause” was actually the programming on the laser used to cut the relief. It was programmed to make a sharp inside corner rather than an appropriate radii and when it momentarily stopped to make the corer the heat cause a microfracture undetectable except by dye pen with controlled heat applied.

The bottom line is that nothing is perfect, and occasionally a flaw will creep into a car that’s impossible for any shop technician to find the “root cause” of and to fix. Some problems can require highly sophisticated equipment and analysis.

There’s a whole field of engineering called “reliability engineering” dedicated to preventing problems from developing in finished cars. But it ain’t perfect. Nothing is. Just as every textbook has a few errors, so too does every car. The “lemon” is the one that has the errors that affect its operation.

Brand new “Lemons” are rare these days because automakers have almost perfected quality control techniques that drastically reduce the imperfections and variations in parts that used to result in “lemons.”

Decades ago, up until the 1980’s, US automakers had relatively poor methods for controlling the quality of individual parts. Some cars got lucky and got all good quality parts. Most cars got average quality parts. Some cars got unlucky and got many poor quality parts. Those were the lemons, whose engines or transmissions would break down prematurely, or were subject go any number of other problems.

There was also some slipshod workmanship. In the '50’s or '60’s car buyers were sometimes advised to avoid buying cars that had been assembled on Mondays (by hung over workers) or Fridays (by workers already thinking about the weekend and not paying attention). Those cars were rumored to be worse in quality than cars assembled in midweek.

The problem with “lemons” was that so many of the parts were poor quality or assembled badly that it would have numerous problems, not just one, and you’d fix one problem only to have another pop up, on and on, without end. A lemon is a rolling pile of endless mechanical and electrical problems. So replacing parts on a lemon is never a final solution, because after you replace one part, another one breaks.

In the 1980’s, Japanese carmakers adopted advanced quality control methods developed by an American named W. Edwards Deming, who had been ignored by US carmakers. Japanese car quality quickly surpassed Detroit car quality, and Japanese carmakers soon started eating Detroit’s lunch.

It took Detroit a couple of decades to catch up and reach rough parity with Japan. Now it’s pretty hard to buy a new “lemon” any more. Pretty much any US/Japanese/European/Korean car is almost guaranteed to go 100,000 miles with proper maintenance.

Agree with the above experts. Even if you get a car with repeated or multiple problems, the dealer and the manufacturer reps need to be able to identify the problem and replace the proper part. If you have ever tried to find an elusive or intermittent problem with your car, that may not be so easy. Especially if it involves electronics or flawed software.

The Monday/Friday cars to be avoided in the past were first attributed to workers not up to par on those days. Further study though I believe, revealed that it was actually the inexperienced temporary replacement worker used to fill in for absent regular employees on Fridays and Mondays. These temporary workers made many errors as they assembled the parts and cars. So the real problem was excessive absenteeism, the cause of which is the subject of many books.

All good posts! I agree that with today’s quality control there are far fewer lemons.

A friend of mine was a master mechanic and was unable to diagnose a rough running AMC car. The owner got another car under the lemon agreement. However, when they took the engine apart just to see what might be the problem they found the cork stopper of a Thermos bottle in the intake manifold. It bobbled around cutting air flow off to various cylinders. Similar rattle problems were often soda bottle welded inside doors.

"The problem with "lemons" was that so many of the parts were poor quality or assembled badly that it would have numerous problems, not just one, and you'd fix one problem only to have another pop up, on and on, without end. A lemon is a rolling pile of endless mechanical and electrical problems. So replacing parts on a lemon is never a final solution, because after you replace one part, another one breaks."


However, I think it is important to distinguish between the occasional “lemon” from a particular manufacturer and models that are just inherently trouble-prone.

Any company has the capacity to turn out a vehicle here and there with one or two seemingly unresolvable problems. Then, you have companies that turn out an endless stream of poor-quality vehicles for a period of several years. Back in the '70s, there were no Lemon Laws, and if there had been, some companies–such as Volvo–might have gone belly-up.

If my '74 Volvo had been plagued with just one or two problems, I might have chalked it up to aberrations. However, since the fuel injection system, the engine itself, the transmission, the entire electrical system, and the paint were all flawed, that car went beyond the modern definition of a “lemon”. Instead, it was a case of poor engineering, poor quality control, and poor assembly quality.

It was only after I had owned the car for a couple of years that I encountered other owners of '72-'75 Volvos who had the exact same ongoing problems that I had with that POS. When essentially every vehicle coming down your assembly line has the same problems, I don’t think that the term “lemon” is adequate to describe the situation.

Luckily, true lemons are not that common anymore, and when they do crop up, there are legal solutions for most owners.

To me anyway, I consider a Lemon to be a new car that has suffered from multiple problems since the day it was new and which exist in a number that could be considered nowhere near normal.
I don’t know that I would consider a single, chronic complaint which may lead to a Lemon Law complaint as being the sign of a Lemon although I do agree that if unresolved it should be in the customer’s favor.

Any production line item is going to have a percentage of problem children be it pop-up toasters, toys, or cars. Some will just be an aberration and could be chalked up to luck of the draw.
The complexity of modern cars means that a lot of issues are not black and white. Electrical and electronic issues are the worst and especially so with intermittents.

An example could be Marnet’s Impala. A few hiccups at first could be explained away but after a few years on a low miles car there were too many hiccups to dismiss as minor glitches.

In my case, what started as a small, defective, part blew up due to dealership mechanic incompetence.

I took my car in for an oil leak (1 year old). I was pretty sure, and the dealership confirmed, this was due to a leaking rear main seal. This was a known issue with a number of these cars so I did not worry too much about it.

The fix was to remove the front half of the car to get the engine and transmission out, then replace the seal.

When the engine/trans was removed, evidently one of the seals for the axle shafts was nicked so that seal needed to be replaced as well. Not a problem except there was a delay due to ordering of the wrong parts.

When I finally got the call my car was ready, I took time off work to go pick it up. The closest dealership was over 100 miles from my home. I got there just as the service department was closing, jumped in the car and took off. About a block down the road I noticed a horrendous banging noise underneath the car over bumps. To me it sounded like sway bar links for suspension. I called the dealership from the road and told them I would be right back. I got back and the service department had all gone home already.

So I left my car there and went home.

A couple days later the dealership delivered my car to me (loose suspension bolt).

After a couple of weeks I noticed a burning oil smell. I had let it go in case they had just got oily fingers on the exhaust. I looked under the car and found oil was leaking at a much higher rate than it had previously.

I ended up taking the car back to the dealership. Many parts were replaced over along with other parts such as the oil pan.

When I went to pick my car back up, I got a few miles and heard a sound like a dry bearing. To me it sounded like it was in the transmission. I pulled over, called the dealership and told them my wife would be bringing the car back to be fixed. My feeling was that they forgot to put oil back in the transmission (manual) after having it out.

My wife waited in the service department the next day for something like 6 hours, they finally came out and told her the transmission oil was low.

When I got the car home, I popped the hood to find many broken parts, lots of sensors with broken plugs and parts now being held together with zip ties.

The dealership had my car for almost 2 months for a repair that was supposed to take 2 days. A car less than one year old now looked like it had been worked on by a teenager with no clue.

Under AZ law, my car was eligible for lemon law protection so I went for it.

I worked in the Nissan plant in Canton, MS back in about 2003, building an addition on to the plant. I snuck away for an hour one day and walked around in a massive parking lot that was full of “practice cars”. Some were half assembled. Some looked 100%. The had DVD players and 18" chrome wheels. They were all there as training tools, although I guess some of them may have been pulled off the line by a QC for faulty work. Either way, it made me kind of sad. A Nissan employee referred to it as the Graveyard.

“Either way, it made me kind of sad. A Nissan employee referred to it as the Graveyard.”

Car manufacturers did the same thing in the 1970s, but if I recall correctly, it was called the Dealer Showroom.
That was a very sad situation.


We bought a new 1987 Ford Taurus that had been on the lot for 6 months. Shortly after we bought it, the AC stopped cooling. We took it to the dealer and they tried to fix it. They rebuilt the compressor and after we got it back, the AC squealed whenever the clutch was engaged. Back it went again. They fuzzed around with it a few more times. After a couple of months, the had tried to fix it 5 times and I notified Ford that a I wanted a new car under the lemon law. When I arrived at the dealership for the last attempt, the service advisor’s eyes got as big as saucers when he looked at his computer. He obviously saw that this was their last try or they owed me a new car. This time they replaced the compressor and all was well. I told them when I first took it in that I thought the deals were rotted because it sat unmoved on the lot so long. They didn’t buy it. I told them the same thing every time I took it in. And they still didn’t buy it. But the last time they did. In this case, the car was a lemon because the dealership staff tried to cheap out on the repair. In the end, they made Ford pay several time more than it should have cost, and it almost cost them a new car. It’s not always a design flaw or poor assembly.

Remember all the rusting amc fenders, a guy told me it was because they were stored in a wahrehous with a leaky roof. The water would pool in the fenders, then rust, spray paint it and go! Electronics are built within acceptable parameters, sometimes stuff goes wrong. I have replaced capacitors in motherboards and lcd tv’s, story was a taiwan company stole the formula, missed an ingredient and capacitors failed way to early. So 5 years ago I did the capacitors in my lcd tv after no power on, 8 bucks for parts, a little soldering I am done. It would have been a major hassle and expense to reprogram new computers to replace the dead computers at work that have been brought back on line by replacing blown capacitors, software, security system keys etc.

I had a lemon Samsung TV earlier this year. Bought late last year, it had intermittent HDMI failures. Each one would require momentarily disconnecting the HDMI cable to force the TV to renegotiate the connection. After 3 months and many board replacements, and many phone calls, Samsung gave me a new TV, a newer model. This one worked fine. Turns out I had a combination of several bad cards plus a marginal cable. The new TV on seeing an HDMI problem would immediately renegotiate the connection, causing only a half second interrupt. But that allowed me to pinpoint the marginal cable.

The reason I didn’t suspect the cable initially is that at that time, both HDMI inputs were failing – the initial bad board problem.

Not one of the many technicians that tried to fix it brought an HDMI checker or a spare cable.

If you didn’t know this, the HDMI connection is very complicated, due to the movie companies trying to stop digital copying.


Statistical random chance pretty much guarantees a lemon-car will happen from time to time. Each part that goes into making a car has a small chance of being on the fritz and the flaw going undetected. Since the number of new cars produced each year is so large, a few cars will have much more than the average number of undetected flaws.

Have you ever played poker with your friends and over the course of the evening you never once get something even close to a good hand? Same thing.

Something else along these same lines, the opposite of a lemon. A charm. That can happen too. An item which coms off the ass’y line which performs considerably better than the typical one off the line. Sometimes design engineers have to purposely degrade the performance of their products to prevent the off-chance of a unit coming off the assembly line which works much better than the other units. Why? B/c if a customer happens to get that particular charmed item, they’ll ask why the second one they buy doesn’t work as good.

Remember all the rusting amc fenders, a guy told me it was because they were stored in a wahrehous with a leaky roof. The water would pool in the fenders, t

Bar far the manufacturer of that era which had major problems with rusty fenders was Chryco. The Darts and Furry’s top fender near the windshield rusted out in 2-3 years of ownership. They were real real bad. The only guy I know who owned a Dart that didn’t rust was a Ziebart dealer.

I had a 73 (I think) Toyoto Corolla. It had rear drive, and was the most unreliable car I ever had.

At 23k miles, when I sold it, it had:
A defective differential, the second one
body rusting through from the inside in many spots
An alternator that was partially shot and could only charge at about 1/3 current
two cylinders with low compression


The scary thing was that some of them looked as if they could be sold as legit cars. Makes you wonder how often that may happen.

“I had a 73 (I think) Toyoto Corolla. It had rear drive, and was the most unreliable car I ever had.”

By and large, the Japanese cars of the '60s & '70s were crap–pure and simple.
My brother’s first wife bought a Datsun SPL-311, a more-or-less copy of an MG.
Unfortunately, it was even less reliable than the car from which it was copied.

In addition to rust issues that began w/in less than a year, it leaked water from underneath the windshield. The convertible top, the boot that covered the top when it was folded, and the tonneau cover were all just a bit too small and as a result you could never fasten all of the snaps securing those canvas parts.

If the ambient temperature was below ~40 degrees, it was almost impossible to get that lemon started. We referred to this as Datsun’s ultimate safety feature, as it prevented you from driving the car if there was even the slightest chance of ice on the roads.

The most appalling part was the fact that the air filter couldn’t be changed unless you removed the side-draft carburetors. The fit in the engine compartment was so tight that the cover plate for the air cleaner housing couldn’t be removed after you took the wing nut off, and unbolting the twin carbs was the only solution.

While I can’t recall the exact details at this point, our mechanic said that there was something…unique…about the design of the front disc brakes that made it unusually difficult to replace the brake pads.

And, the dealership was of no help whatsoever. At that time, Datsun was essentially giving franchises to anyone who could pay the price, with no follow-up or supervision of their dealerships. This particular Datsun dealership’s “service department” consisted solely of one old man who washed and vacuumed the cars prior to delivery.

As we discovered, any time that a car was brought in for service, as soon as the customer departed, the car was driven around the corner to a Gulf gas station. The Gulf station owner had neither the training, the specialized tools, nor the interest in actually repairing these highly-flawed Japanese pieces of junk, and as a result, the car was always returned to us w/o any of the problems being resolved.

Eventually we just stopped taking the car to the dealership because the owner (who wore a shiny suit and was surely a member of La Cosa Nostra) convinced my brother that it was not in his best interests to keep complaining about the car.

My “lemon” was a brand new 1974 Chevy Monte Carlo. It was an “experimental?” model from the factory and it was rushed into the new car market way too fast. It had a catalytic converter, an HEI distributor with no silicone heat sink under the ignition module, regular plugs gapped at .035 and a wiring block installed incorrectly.

I was headed to arbitration when Chevrolet stepped in and bought the car back from me at a premium. The new Monte Carlo that I bought to replace the “lemon” gave me years of good service without any problems at all. I’m sure they learned a lot from that lemon so that the 1975 models were a lot better than they would have been otherwise. Maybe lemons are a good thing sometimes but mine was a royal pain in the posterior for several weeks.