Using a OBD2 reader on a test drive

[Elixer]

I usually go to a dealer, ask to test drive a car, and hook it up and do the normal driving routine, and see how everything checks out. Seems like a no brainer right? (Yes, I know it won't find everything, but it does plot the data and you can tell if something seems odd or not)

Well, this time around, sales guy wanted to come with, which I find odd, but whatever, and when I went to plug it in, and he objected. I said, it is only a reader, and he goes "I GAVE YOU THE CARFAX REPORT!"
I was like, yeah, and? That don't provide the same information. He then goes, 'THE REPORT COVERS EVERYTHING YOU NEED TO KNOW! IT IS ILLEGAL IF I PLUG IT IN!'.
I go, come again? He goes, 'IT IS ILLEGAL, IT IS HACKING THE CAR!' I go, it is a reader, nothing more, we can even ask your shop, and he goes 'NOT WORTH MY TIME!', I go. Wrong, it is not worth MY time.

Since when does Carfax/autocheck reports contain anything useful for anything besides checking for accidents/salvage/flood stuff?

 

[dave_the_nerd]

Sounds like somebody who won't be selling cars for long.

 

[lxskllr]

I don't see any scenario of me buying a car from them that didn't involve the salesman standing in front of me with his pants around his ankles, and handing me $100 bills while apologizing til I said it was sufficient.

 

[Fenixgoon]

sounds like a car salesman who doesn't know much about cars. shocking.

 

[NutBucket]

Yep. Move on. It's amazing how little car salesmen know sometimes....even in their bread and butter products.

 

[tsupersonic]

You're right to walk out. Definitely not worth your time if a test drive starts like that...not that it matters, what car was it btw?

 

[Raizinman]

What were you hoping to find? If the CEL was off, then your reader would not find anything. Similarly, if your reader is able to see old codes then they are obviously repaired (since the CEL is off), so I'm wondering, why the big deal about wanting to plug in a reader? If I was a salesman and someone started to plug in something, I would also be hesitant. How does he know it is just a reader and not something that could damage or change the settings? For the most part, the Carfax will show the service records for the car including any OBDII repairs.

 

[Rifter]

What were you hoping to find? If the CEL was off, then your reader would not find anything. Similarly, if your reader is able to see old codes then they are obviously repaired (since the CEL is off), so I'm wondering, why the big deal about wanting to plug in a reader? If I was a salesman and someone started to plug in something, I would also be hesitant. How does he know it is just a reader and not something that could damage or change the settings? For the most part, the Carfax will show the service records for the car including any OBDII repairs.

You can use most OBD readers to plot data from all the sensors and record it, this will give you an idea if anything is wrong with a vehicle, CEL or not is irreverent to its use in this case. I do the same thing as OP, i would have walked too.

 

[Raizinman]

If the sensors are within range they will not be a CEL. Plotting the data and recording the sensor movement is absolutely irrelevant since everything is working correctly. If I was selling a vehicle I would be highly suspicion of anyone trying to plug in something to the OBDII port especially if I was not familiar with the brand of reader.


The OP had no knowledge that Carfax reports show service records and would likely have shown any OBDII repairs. This shows his automotive knowledge; it’s also possible that his alleged reader might tamper with some of the settings?


I would never allow any individual to start plugging things into the car and then have to argue later if they caused damage. Instead, if he really wants a reading of the sensors, let him pay a shop (which has insurance) to pull the sensor data, which I have to believe would not mean that much to him. I would tend to think that he is just trying to show off that he might have some mechanical knowledge by totting around his $29 OBDII reader.

 

[Rifter]

If the sensors are within range they will not be a CEL. Plotting the data and recording the sensor movement is absolutely irrelevant since everything is working correctly. If I was selling a vehicle I would be highly suspicion of anyone trying to plug in something to the OBDII port especially if I was not familiar with the brand of reader.


The OP had no knowledge that Carfax reports show service records and would likely have shown any OBDII repairs. This shows his automotive knowledge; it’s also possible that his alleged reader might tamper with some of the settings?


I would never allow any individual to start plugging things into the car and then have to argue later if they caused damage. Instead, if he really wants a reading of the sensors, let him pay a shop (which has insurance) to pull the sensor data, which I have to believe would not mean that much to him. I would tend to think that he is just trying to show off that he might have some mechanical knowledge by totting around his $29 OBDII reader.

The fact that you believe a CEL is the only way to tell if everything is working correctly does not mean that it is true. ECU's are not perfect when attempting to detect faults, they are only as smart as the people who program them.

A friend of mine once called me to look at his car with my reader because his fuel economy was not as good as it should be in his new car(new to him, was a 10 year old vehicle). I hooked up my reader and noticed no CEL's, and at first no anomaly's with any data being reported. Left it in the car for a few hours and we drove around, went for lunch, then returned to his place to look over the logs. The data for the O2 sensor did not change at all the whole time, like even a decimal place had not changed. heatup and cooldown of engine should have changed O2 sensor readings but sensor was reporting exact same resistance to the decimal place to the ECU for the whole drive. Go to remove O2 sensor to check it manually expecting it to be cooked and find it doesnt exist, previous owner had installed a plug where the o2 sensor should be and a resistor on the wiring harness to fool the ECU and not throw a CEL as they actually researched this enough to pick a resistor that was within the sensors operational range. This is but one of many situations where one would think the vehicle is fine, its not throwing a CEL afterall, but in reality there is an issue, and if you never bother to look for issues, you will never find them.

CEL's are great as a diagnostic tool, but they should not be the only tool in your bag.

 

[Elixer]

OK, now I am curious, how many of you guys request to see the underside of the used car on a lift before buying it? I know people look at the engine, but, dealers usually clean that off.

If you don't do that, how can you tell how rusted the rocker panels (or anything else) are, since they rust from the inside out?

 

[lxskllr]

OK, now I am curious, how many of you guys request to see the underside of the used car on a lift before buying it? I know people look at the engine, but, dealers usually clean that off.

If you don't do that, how can you tell how rusted the rocker panels (or anything else) are, since they rust from the inside out?

I don't need it on a lift, but I'll get under a car to check it out. I guess it helps that I don't buy low clearance vehicles.

 

[Rifter]

OK, now I am curious, how many of you guys request to see the underside of the used car on a lift before buying it? I know people look at the engine, but, dealers usually clean that off.

If you don't do that, how can you tell how rusted the rocker panels (or anything else) are, since they rust from the inside out?

I always carry a magnet and a small microfiber cloth when inspecting a used vehicle. Put the microfiber cloth on the rocker or any metal you think may be rusted/bondo to protect the paint/finish and place the magnet on it and move it around. If magnet isnt sticking firmly it may be rusting out from the inside, if magnet falls off its been bondo/filled and there is no real metal left.

And i always 100% look under it, preferably on a lift.

 

[MtnMan]

The question you didn't ask, but should have is: "What the hell are trying to hide?"

 

[mindless1]

Just chalk it up to another ignorant paranoid soul in the world. It's common in certain temporary professions like sales and service. Heck I've been to used car dealerships where they flat out refused to tell me the (cash) price of the vehicle, would only talk financing if I bent over first. lol.

 

[MtnMan]

I have found that turning and walking toward the door has caused them to reconsider my offer.

 

[Raizinman]

When selling a used car, all owners will allow non-invasive inspections. That means testing all the windows, open and close the doors, try all the lights, wipers and horn. Basically, touch, try and feel anything you want including a test drive. What most dealerships and owners will start to complain about are invasive inspections. Let’s say you want to check the front bearings and want to remove the front wheel? What if you wanted to start pulling back the carpet to check for a flooded car? What if you wanted to remove a spark plug to check for last tune up? I could easily come up with a page of these types of checks that include hooking up any type of diagnostic scanner.


The correct response to tell a customer is: If you want to take the vehicle to a certified garage (meaning insured) for an inspection, or we can do that here in our shop (on your dime). Otherwise, you are not going to start disassembling the vehicle here in our used car lot. The potential for something to go wrong is too high.


What happens if you break something when disassembling or re-assembling?

What happens if your scanner caused a problem while running a test?


How does the dealership or owner of the vehicle know that you know what you are doing? Or if you might damage the vehicle? Just because you own a scanner? LOL


Sorry, dealerships would rather you walk away than damage any of their cars. These are the type of customers we would rather give to our competition. So when you smile and turn and walk away when they refuse to allow your invasive inspection, keep in mind that they are also smiling for not having to deal with customers like you.

 

[BarkingGhostar]

And what liability does the potential buyer agree to if said code reader happens to cause and issue that damages the vehicle? Not siding with this sales person (idiot), but there are two sides to everything. If I were selling a personal vehicle I would allow my own code reader to be attached, but certainly not a reader from some potential buyer UNLESS they take full financial responsibility if something happens. Even then I'm not inclined to allow someone to connect their electronic device to my property.

The alternative would have been to ask the sales person (ahem, idiot) to get their shop to connect their code reader for you to inspect the results. This keeps the liability in the seller's hands and any refusal would be your natural unwillingness to do business with the dealership. But politely informing him it isn't hacking (every emission place would be doing it) and asking their own mechanic to do it would be enough to mitigate the situation, no?

 

[monkeydelmagico]

Only time I whip out the code reader is if the POS I'm buying is throwing a code. Why bother on a car that's not showing any idiot lights?

 

[Elixer]

Only time I whip out the code reader is if the POS I'm buying is throwing a code. Why bother on a car that's not showing any idiot lights?

How about reading post #10 & #8 in this thread?
It isn't just about the idiot lights...

 

[Zorba]

If the sensors are within range they will not be a CEL. Plotting the data and recording the sensor movement is absolutely irrelevant since everything is working correctly. If I was selling a vehicle I would be highly suspicion of anyone trying to plug in something to the OBDII port especially if I was not familiar with the brand of reader.


The OP had no knowledge that Carfax reports show service records and would likely have shown any OBDII repairs. This shows his automotive knowledge; it’s also possible that his alleged reader might tamper with some of the settings?


I would never allow any individual to start plugging things into the car and then have to argue later if they caused damage. Instead, if he really wants a reading of the sensors, let him pay a shop (which has insurance) to pull the sensor data, which I have to believe would not mean that much to him. I would tend to think that he is just trying to show off that he might have some mechanical knowledge by totting around his $29 OBDII reader.

Carfax only shows repairs done at shops that report to Carfax. My legacy with 165K on the clock had one shop report ever. The only CEL it ever threw I fixed myself, but it would've been very easy to hide as it was an intermittent problem. Really you could clear the vast majority of codes right before a test drive and they wouldn't come back on during a normal test drive.

 

[Raizinman]

As of November 15, 1990 Federal Law prohibit ANYONE from removing or rendering inoperative any emission control device or element of design that is installed on a motor vehicle or motor vehicle engine. Anyone who breaks this law can be penalized as much as $2,500 for each motor vehicle or motor vehicle engine they tamper with. Dealerships and manufactures can be penalized up to $25,000 for each violation. This prohibition is one of the 1990 Amendments to the US Clean Air Act.


What is Tampering? You are tampering if you remove, bypass, defeat, disconnect, damage or in any way render ineffective any emission control device or element of design that has been installed on a motor vehicle or motor vehicle engine or have someone else do it for you.


As a technician, you are at risk even if you give instructions to a customer on how to tamper with his vehicle.


Tampering even by a car owner is against the Federal Law and is also prohibited by state law in most states.


If you purchased a vehicle that you later found out was tampered with you should contact the original seller to make the necessary repairs to put the vehicles emission system back into compliance.


This is your ‘safety’ for not having to check every vehicle with your handy scanner. Because of the penalty involved, most people (and especially dealerships) will not tamper with the emission system. For those that do tamper, they will find out soon the penalty can be costly.


All technicians should know this law.

 

[jlee]

If the sensors are within range they will not be a CEL. Plotting the data and recording the sensor movement is absolutely irrelevant since everything is working correctly. If I was selling a vehicle I would be highly suspicion of anyone trying to plug in something to the OBDII port especially if I was not familiar with the brand of reader.


The OP had no knowledge that Carfax reports show service records and would likely have shown any OBDII repairs. This shows his automotive knowledge; it’s also possible that his alleged reader might tamper with some of the settings?


I would never allow any individual to start plugging things into the car and then have to argue later if they caused damage. Instead, if he really wants a reading of the sensors, let him pay a shop (which has insurance) to pull the sensor data, which I have to believe would not mean that much to him. I would tend to think that he is just trying to show off that he might have some mechanical knowledge by totting around his $29 OBDII reader.

On the topic of automotive knowledge, please read this: http://www.fiestafaction.com/forums/threads/33363-What-are-quot-Pending-quot-OBD-II-Codes

Also, if someone clears all codes and then puts a car up for sale immediately, the emissions monitors will not all be in a 'ready' state. A car can't pass an OBDII emissions inspection until enough monitors have gone 'ready.' Meaning, there is a time window for certain codes between clearing them and their reactivation. If a car shows no codes but all of the emissions monitors are not ready, you can't definitively claim that the car is fine.

https://dmv.ny.gov/brochure/what-do-you-mean-my-cars-not-ready

Causes of a "not ready" report:

• Recent vehicle repairs in which diagnostic trouble codes have been cleared with a OBDII scan tool; or,
• if the battery had been recently disconnected or replaced; or,
• if the vehicle's computer requires a software update; or,
• a pending problem has not yet illuminated the "check engine" light.

 

[lxskllr]

As of November 15, 1990 Federal Law prohibit ANYONE from removing or rendering inoperative any emission control device or element of design that is installed on a motor vehicle or motor vehicle engine. Anyone who breaks this law can be penalized as much as $2,500 for each motor vehicle or motor vehicle engine they tamper with. Dealerships and manufactures can be penalized up to $25,000 for each violation. This prohibition is one of the 1990 Amendments to the US Clean Air Act.


What is Tampering? You are tampering if you remove, bypass, defeat, disconnect, damage or in any way render ineffective any emission control device or element of design that has been installed on a motor vehicle or motor vehicle engine or have someone else do it for you.


As a technician, you are at risk even if you give instructions to a customer on how to tamper with his vehicle.


Tampering even by a car owner is against the Federal Law and is also prohibited by state law in most states.


If you purchased a vehicle that you later found out was tampered with you should contact the original seller to make the necessary repairs to put the vehicles emission system back into compliance.


This is your ‘safety’ for not having to check every vehicle with your handy scanner. Because of the penalty involved, most people (and especially dealerships) will not tamper with the emission system. For those that do tamper, they will find out soon the penalty can be costly.


All technicians should know this law.

Rolling back the odometer is illegal too, but that never stopped anyone back in the days when it was easy to do. I don't trust policy for anything. Policy's only a solemn pinky swear stating you'll do/have done something. I'd rather prove it using my own eyes/tools.

 

[NutBucket]

So the simple answer is to witness 4th emissions test in person. Eliminates quite a few methods to hide a cel.

And when I sold a car that wasn't emissions compliant, I provided the test certificate. Note that car failed visual but passed all other tests.