How often do garages mis-diagnose faults?

[-Mike-]

I'm not sure why I'm getting the book thrown at me by some in this thread, I used it purely as an example as to why I wondered the question in my OP. I am not a mechanic, I don't do anything mechanical for my job and yet am getting jumped on!

What I found slightly amusing is - if he had let them replace the fuel pump, it still would have presented the same issue. What do they do when they've billed a customer stupid money and the problem is still present? Do the garages get away with this?

 

[[TW]Fox]

I'm not sure why I'm getting the book thrown at me by some in this thread

Perhaps they work in garages and feel it appropriate to bill customers for inability to find faults

 

[Jester*]

Are there any other industries where incompetence is more profitable than competence?

Just randomly replace stuff and blag your way through, the more work you do, however much of its totally pointless, the more you can bill the customer for.

Yes the company that manage the estate I live on have been billing (amongst a massive list of things) electricity for a street light that was not even installed.

But because it is in the deeds we are legally obliged to pay (cheers labour xD). Although we are challenging everything and effectively refusing to pay any charges until they sort it out.

OM is the management company if anyone wants to avoid estates managed by these bunch of chancers.

 

[MatteH Oxford]

Why are certain people criticising the OP?

For ****ging garage diagnosis methods off yet using similar guessing game diagnosis methods himself, and getting lucky with the end result. There were numerous other potential causes for this fault that were not checked out. Theo one thing he did test wasn't mentioned in the OP

Not too hard to work out really, even if you don't have genuine experience and training within the motor industry.

 

[Hades]

For ****ging garage diagnosis methods off yet using similar guessing game diagnosis methods himself, and getting lucky with the end result. There were numerous other potential causes for this fault that were not checked out. Theo one thing he did test wasn't mentioned in the OP

Not too hard to work out really, even if you don't have genuine experience and training within the motor industry.

Well he didn't really do exactly the same as the garage:

Garage: Read code, assume it must be the most expensive part and recommend that is replaced.

OP: Use code to search a knowledge base (the internet/forums) for similar issues. Find a possible cause is a much cheaper component and try replacing that one first.

OP's approach is far more sensible and I would have hoped that the garage would offer several possibilities to the customer and discuss the next steps together. But they rarely do.

 

[[TW]Fox]

For ****ging garage diagnosis methods off yet using similar guessing game diagnosis methods himself, and getting lucky with the end result.

So?

A PROFESSIONAL charged him money for the guessing game. Guessing is fine when you are doing it yourself at zero charge. Guessing is unacceptable when you are paying a so called expert to troubleshoot for you.

 

[Liquidfox]

Are there any other industries where incompetence is more profitable than competence?

IT?

If I can fix it in 1 hour as I know exactly what the fault is and how to fix it, but a colleague doesn't and it takes him 3 hours to find out what it is and fix it, who does my boss prefer?

 

[Howard]

I have no first-hand experience of dealing with a garage in the way of them diagnosing a fault for me, but surely a garage can't expect you to pay them for the replacement of an item which hasn't fixed a problem, a practice which seems rife according to this thread?

 

[-Mike-]

For ****ging garage diagnosis methods off yet using similar guessing game diagnosis methods himself, and getting lucky with the end result. There were numerous other potential causes for this fault that were not checked out. Theo one thing he did test wasn't mentioned in the OP

Not too hard to work out really, even if you don't have genuine experience and training within the motor industry.

You are joking right? You a mechanic per chance?

I married previous experience of such a fault on my 306, with a fault code and came up with an answer. I then hopped onto ye olde google to see ACTUAL owners posting about the ACTUAL problem and once again being ripped off by garages just throwing peoples money around to replace a part that isn't even faulty. I measured the resistance of the part, it read out of range. You know... the same kind of thing a doctor might do with blood pressure or similar?

My 'lucky' result was a shed load better than the garages epic fail result which would have meant a 1k bill with the fault still present.

Well he didn't really do exactly the same as the garage:

Garage: Read code, assume it must be the most expensive part and recommend that is replaced.

OP: Use code to search a knowledge base (the internet/forums) for similar issues. Find a possible cause is a much cheaper component and try replacing that one first.

OP's approach is far more sensible and I would have hoped that the garage would offer several possibilities to the customer and discuss the next steps together. But they rarely do.

Thank you!

So?

A PROFESSIONAL charged him money for the guessing game. Guessing is fine when you are doing it yourself at zero charge. Guessing is unacceptable when you are paying a so called expert to troubleshoot for you.

Again, thank you Fox.

To be honest I can't believe this guys attitude, anyone would think I'd intentionally written my car off or killed someones cat on purpose by his responses.

 

[lordrobs]

I have no first-hand experience of dealing with a garage in the way of them diagnosing a fault for me, but surely a garage can't expect you to pay them for the replacement of an item which hasn't fixed a problem, a practice which seems rife according to this thread?

I haven't ever had that happen. Two of my issues were under warranty but the garage would have quite happily have me pay for a new alternator when it wasn't the cause of the problem.

To be fair it only took one firm phone call and a flat refusal of their offers of a free service followed by free service and MOT to get get my full money back including courtesy car costs plus I kept the new alternator as my old one was sent back as an exchange item

 

[Tute]

I have no first-hand experience of dealing with a garage in the way of them diagnosing a fault for me, but surely a garage can't expect you to pay them for the replacement of an item which hasn't fixed a problem, a practice which seems rife according to this thread?

I was under the impression this is just "how it works"?

I paid to have my MAF sensor replaced when fault-finding and it made no difference despite costing me almost £100. This was done on the recommendation of the main dealer.

 

[-Mike-]

You should be demanding your money back if it hasn't fixed it - especially at a main dealer.

 

[MatteH Oxford]

So?

A PROFESSIONAL charged him money for the guessing game. Guessing is fine when you are doing it yourself at zero charge. Guessing is unacceptable when you are paying a so called expert to troubleshoot for you.

It's not being done with zero charge when replacement parts are involved. OP guessed due to having neither the experience or training to say for certain the part was at fault. If there was a supply voltage issue in the circuit (that could have been rectified), the part may well functioned o.k. as it was. He certainly didn't hook up a scope and look at the waveform and actually have real time evidence that this part was faulty.

Seeing as the OP performed no other tests that should have been carried out as part of a complete assessment of this circuit, then they should accept that their methods are not much better than the what they are complaining about.

I suggest people like yourself Fox, should stick really to BMW trim levels as I have probably forgotten more than you will ever know about fixing cars

 

[-Mike-]

It's not being done with zero charge when replacement parts are involved. OP guessed due to having neither the experience or training to say for certain the part was at fault. If there was a supply voltage issue in the circuit (that could have been rectified), the part may well functioned o.k. as it was. He certainly didn't hook up a scope and look at the waveform and actually have real time evidence that this part was faulty.

Seeing as the OP performed no other tests that should have been carried out as part of a complete assessment of this circuit, then they should accept that their methods are not much better than the what they are complaining about.

I suggest people like yourself Fox, should stick really to BMW trim levels as I have probably forgotten more than you will ever know about fixing cars

The garage with the experience and training, and even Vauxhall dealerships according to other posts elsewhere guess WITH the experience and training that its the fuel pump. Guess what - It isn't the fuel pump.

How did I guess? I tested the resistance of the sensor both COLD and HOT and I'll state this again incase you miss it THE PART WAS OUT OF RANGE.

Also to say I didn't carry out a complete assessment, neither did the garage, they read the code and went OH LOOK its fuel pump. Undoubtedly the same thing you would have done.

Tell me something mr pro hero mechanic - I have experience from the past of rev counter issues, and guess what... ten years ago I too tested the values on my sensor on my 306... it too, was out of range. How do you think people get experience of something? Normally by it happening to them.

Edit : Can't be bothered with half of it. I fixed the fault, it cost him EXACTLY the replacement sensor. You aren't a mechanic anymore so lets be moving on now. As for insulting Fox..... charmer !

 

[peige]

I've been properly stung by an independent miss diagnosing the fault, it came down to them using outdated diagnosis equipment/codes. They charged me for a new CAT, turned out the problem was the EGR valve, a fairly common modern diesel engine fault. I got nowhere with the indi, I was properly swindled and in the end had to put it down to experience.

I resolved to stick with main dealers in the future, at least they have a proper way of handling complaints and you can escalate the problem through the dealership. With an indi you are basically stuck the moment they put down the phone on you.

 

[Hades]

It's not being done with zero charge when replacement parts are involved. OP guessed due to having neither the experience or training to say for certain the part was at fault. If there was a supply voltage issue in the circuit (that could have been rectified), the part may well functioned o.k. as it was. He certainly didn't hook up a scope and look at the waveform and actually have real time evidence that this part was faulty.

Seeing as the OP performed no other tests that should have been carried out as part of a complete assessment of this circuit, then they should accept that their methods are not much better than the what they are complaining about.

I suggest people like yourself Fox, should stick really to BMW trim levels as I have probably forgotten more than you will ever know about fixing cars

From the information given the OP did more testing and investigation than an allegedly trained professional. As a result of him doing that he correctly identified the problem.

The trained and experienced garage guessed. The OP didn't from what I can see. I think we ask agree that a decent mechanic should do additional checks but the reality nowadays is that garages employ fitters rather than mechanics and charge the general public for a service that isn't what the general public expect.

It's a valuable lesson to all of us to ask the following questions whenever a garage diagnoses a fault:

1) How do you know that is the cause of the problem?
2) What tests did you perform to come to that conclusion?
3) Are there any other tests that could verify it?
4) What else could it be?
5) If the diagnosis is wrong then who pays for the replacement part that wasn't needed?

I guess that most small garages wouldn't give answers that people would like but at least that conversation up front makes sure everyone knows the situation.

 

[BigglesPiP]

Shame ATA hasn't really caught on, their master technician level is hard to get and you can check on-line which garages have someone that can actually do their job, but most garages seem to have stopped bothering to let their staff keep it current.

Mechanic is still a career that failing students get pushed towards, and they're only good for changing tyres.

 

[[TW]Fox]

Seeing as the OP performed no other tests that should have been carried out as part of a complete assessment of this circuit, then they should accept that their methods are not much better than the what they are complaining about.

You continue to miss the point. His methods don't need to be better, he is an unskilled amatuer who is not charging for professional services. The garage is the opposite.

I suggest people like yourself Fox, should stick really to BMW trim levels as I have probably forgotten more than you will ever know about fixing cars

Not sure I understand the point in this particular quip, I've never claimed to know how to fix cars. I'm reasonably open with the lack of mechanical skills I have. But again, not really relevant is it?

The point is the garage didn't find the problem but charged him anyway. Even if they get it wrong or don't help they still expect payment for the time they wasted. There is therefore no real difference to the garage whether they fix the problem or not, somebody is paying for the time eihter way!

 

[MatteH Oxford]

As a result of him doing that he correctly identified the problem.

Potentially.

Just because a part is out of range that does not mean it is 100% at fault, nor does replacing it mean you've correctly rectified the problem, even if the vehicle now appears to run O.K.

The "faulty" part may well be o.k., at least well enough to function if other small faults (that could still be present on that vehicle) were checked and rectified as such. I'd at least check and confirm a part was faulty before replacing one, I certainly wouldn't replace something on the basis there was a fault code showing. So with regards to common faults, they can be a help to resolve issues or point you towards the general direction of the cause of an issue. Sometimes though they can be completely wrong - how often do you see forum threads where the poster has chucked parts at a vehicle with no success? Far more often than the "result" in this one, objectively speaking.

I have to say that I rarely see anything on the internet forums with regards to properly explaining how to check wiring, supply voltage, earth condition etc. As for circuit design & function, pretty much forget it. No so much a problem for me as I can suss out quite a bit from a diagram but even they can be hard to get hold of.

I think the main issue facing technicians is lack of technical information on the function of certain components and systems, it's especially hard for anyone other than a main dealer to access critical information.

From my experience there is also a bit of a culture of not sharing skills and info, quite a few top level technicians have quite frankly, terrible egos with no sense of self depreciation or have much compassion towards their colleagues especially apprentices. Mind you, for what you have to know & the skills required to be a good technician, the pay & conditions aren't exactly that great. It's part of the reason I went into the building trade, I earn nearly 2x as I would stuck in a dealership.

 

[Gaygle]

A lot of faults on cars are the same old design flaws that 1000s of other people have experienced. Often through internet research, i can say with a high probability what the problem is when my car has a problem.

This can become annoying sometimes when you personally are pretty sure you know what the problem is, but you don't want to be rude to the mechanic who you are paying for his skills.

Unfortunately, it's normally dealers that are awful at this and sometimes require a gentle push in the right direction. Unless there is a fault code - dealers don't want to know. Even if there is a fault code, it's hit and miss whether they'll actually get the correct part replaced 1st time.