HI NEED A LITTLE HELP WITH ERROR CODES ON MERCEDES GLC 2LITRE 2017

[hafster]

Hi i hope you are all well,

i was wondering if there are any mechanics on here that can help me with a problem i have. i am just about to buy a mercedes benz glc 2 litre diesel 2017 car from a garage so i decided to use a ODB2 scanner on the car to see if it was all above board and it came up with a few error codes, now the garage tell me that they must be old and may just need clearing but as they had not made me aware of any of this at the start i have started to doubt what they are saying about the health of the car.
i have put pictures of the error codes on here so you can have a look and maybe help me understand them and if it is worth buying this car. i would be very greatful for any help.
thanks.

 

[mioba]

Not sure what the issue is as all the codes are archive code.

ie old stored codes.

 

[supernoodle]

If it only says "Test failed since last DTC clear," yes has happened previously but not present now. If it says "Test failed since last DTC clear, Test not completed this operation cycle" you cannot be sure if still an issue or not. That means the fault did happen previously but the conditions for the module to run the diagnostic check again have not been met yet.
Conditions for the modules to run the diagnostic could be engine running, battery voltage, time since start, temperature, some other fault not being present, ie could be anything. Realistically you'll never know. Generally missing comms faults, the Uxxx DTCs, should run as long as the modules are all awake, so if you read codes with engine running everything should be awake for sure.

 

[Botus]

I'd ONLY be buying a relatively new Mercedes from a main dealer as approved used...

what you have there is exactly why modern cars are more temperamental and more costly to run that they used to be...

being a diesel of this age could well land you with a bill for £1200 before you even get home.... check out posts on NOx sensors, and EML lights on after Dieselgate Emission updates - all of which would have been better spent on a far nicer legit car from a main dealer

 

[hafster]

If it only says "Test failed since last DTC clear," yes has happened previously but not present now. If it says "Test failed since last DTC clear, Test not completed this operation cycle" you cannot be sure if still an issue or not. That means the fault did happen previously but the conditions for the module to run the diagnostic check again have not been met yet.
Conditions for the modules to run the diagnostic could be engine running, battery voltage, time since start, temperature, some other fault not being present, ie could be anything. Realistically you'll never know. Generally missing comms faults, the Uxxx DTCs, should run as long as the modules are all awake, so if you read codes with engine running everything should be awake for sure.

If it only says "Test failed since last DTC clear," yes has happened previously but not present now. If it says "Test failed since last DTC clear, Test not completed this operation cycle" you cannot be sure if still an issue or not. That means the fault did happen previously but the conditions for the module to run the diagnostic check again have not been met yet.
Conditions for the modules to run the diagnostic could be engine running, battery voltage, time since start, temperature, some other fault not being present, ie could be anything. Realistically you'll never know. Generally missing comms faults, the Uxxx DTCs, should run as long as the modules are all awake, so if you read codes with engine running everything should be awake for sure.

Hi
Thanks for the replies.
I did not turn on the engine i only had the ignition on so maybe thats why it didnt manage to complete the test cycle, i will have to make sure it is on the next time.
Thanks again

 

[hafster]

Not sure what the issue is as all the codes are archive code.

ie old stored codes.

hi
so you dont think there is any problem with the car?

 

[hafster]

Hi
Thanks for the replies.
I did not turn on the engine i only had the ignition on so maybe thats why it didnt manage to complete the test cycle, i will have to make sure it is on the next time.
Thanks again

hi

also what about the codes were it doesnt state that it couldnt complete the test cycle are they not a problem aswell?

 

[mioba]

They are all archiverd codes.
Pending would be a concern.
You wont buy a car without a test drive, so thats when to test again.

Why not buy such a new car from a dealers.

 

[hafster]

Ok cheers for that i will scan it again when i go to see it again and i am now considering buying it from the actual dealers even tho the same car is 4k more but the peace of mind might be worth it also this car is from Sytner so i thought it would be ok as they are such a big company.

 

[supernoodle]

Single trip faults don't go pending. Faults that don't set the MIL are often single trip.

Hafster, I'd suggest you read the PID for distance since last DTC clear. If it was many miles ago, that will give you a warm feeling that the garage hasn't been trying to hide things. If however someone cleared the faults very recently, that's a little suspicious.
Read the freeze frame data too, that should indicate when the faults were set.

The missing comms errors could be where its had some work done in the past and someone was disconnecting modules. Even flat batteries can cause such faults. Given that some of those faults are between transmission and engine modules, I expect you'd notice an issue of they were still going to fail.

Do, if nothing bad comes off the above points, it might not all be bad. I very much doubt there's a car out there that has never had a fault code set. If you go to a Merc dealer I bet they will
hook up Star and clear any codes before they go on the forecourt anyway.

 

[hafster]

Hi,

i have spoken to sytner select where the car is being sold and their workshop said the following:

Email from the work shop

The fault codes are previous/old fault codes. The time stamp on the faults was from June 2021. It seems like the battery had gone flat sometime in June 2021, causing these fault codes to be NOT PRESENT/OR ACTIVE when we have plugged the car in. These are old codes as they haven’t come back on after clearing and the car being road tested.

Many Thanks

J. D

Workshop Manager

What do you all think??

i am going to see the car again on the weekend so i will scan the car again but this time with the engine on and hopefully see what comes up.

 

[mioba]

As mentioned they are all archived codes. To clarify historical codes that have beem rectified.

 

[Droverunner]

I have seen a similar collection of fault codes on different makes over the years. Once a near dead battery.... another time where the code reader was faulty showing up non-communication... and when a mobile locksmith was coding a new key and introduced a whole page of similar faults.

In each case clearing the codes and starting/driving the vehicle resolved them.

 

[hafster]

Hi everyone just thought id give an update on my situation, it turns out all the codes were archived codes in the end so i have bought the car and it has been all running well so far, thanks to everyone for their help and all the best.