What the **** are diagnostics for?

A

andysat

Lifer
Hi all-spoke to the stealers today about my catalytic problem (nightmare)-they basically told me AGAIN that they could fit the cat and the emission light could come on!-"we have to follow a process" he told me (indy had said the same but I thought the stealers had more 'sophisticated' equipment)
So basically WTF are we paying £100+ to diagnose a fault if the said fault cannot be rectified without a list of parts needing to be fitted! :headbang:
Sorry for the rant but FFS!!! :thumbsdown:
 
Unfortunately the mantra is now
"Swap bits out until problem solved"
They make the most money that way.
if they can't (be arsed) to do further diagnostics such as taking readings and comparing against what they should be/another car.
or
If they have no further diagnostic tools, then the process should be

'start at the most likely'
or
'start at the cheapest'

depending on how you look at it if your parts or labour target needs a boost.
See if you can get them to agree to take the parts back off and not charge you for them if they don't solve the problem. They may still want to charge you the labour for fitting and removal though.

Fault finding intermittent faults is a PITA ( I do it at least 1 day a week) and can be software related about 50% of the time.

Our E46 330 ci used to have it the same light come on, but it went back off again after three or four key-in:start:stop:key-out as long as you didn't press the accelerator when starting...... We thought it might be fuel quality related, but in the end we decided it was a 'naughty' light for driving too enthusiastically :lol:

From your posts, I'm not sure you're ready to ignore it though.
Hope you find either a solution or inner peace and acceptance :wink:
 
I don't quite understand? I mean they charge a ridiculous amount of money to plug a computer into your car. Is that the main thing you're ranting about? If so why don't you buy a cable and software yourself? That's what I did.
 
Talksthetorque said:
I think Andy's moaning that that's all they do - then they start trying to ream you for bits, saying it 'might' work instead of doing 'proper' diagnosis.
Have a look here
for some history. :thumbsup:
Click to expand...
Yes that's it-its bad enough to be tipped upside down for the diagnosis fee-but for them to then say its a process of elimination! :thumbsdown:
 
Talksthetorque said:
Unfortunately the mantra is now
"Swap bits out until problem solved"
They make the most money that way.
if they can't (be arsed) to do further diagnostics such as taking readings and comparing against what they should be/another car.
or
If they have no further diagnostic tools, then the process should be

'start at the most likely'
or
'start at the cheapest'

depending on how you look at it if your parts or labour target needs a boost.
See if you can get them to agree to take the parts back off and not charge you for them if they don't solve the problem. They may still want to charge you the labour for fitting and removal though.

Fault finding intermittent faults is a PITA ( I do it at least 1 day a week) and can be software related about 50% of the time.

Our E46 330 ci used to have it the same light come on, but it went back off again after three or four key-in:start:stop:key-out as long as you didn't press the accelerator when starting...... We thought it might be fuel quality related, but in the end we decided it was a 'naughty' light for driving too enthusiastically :lol:

From your posts, I'm not sure you're ready to ignore it though.
Hope you find either a solution or inner peace and acceptance :wink:
Click to expand...
I did ask him if I would be due reimbursement if the light came on again (as apparently the cat is the last thing on the list to do)-no I was told because there must be another underlying problem :headbang:
 
It was the 2.2 but last week on my quest to pick up a BMW roadster i was onto a 96k 2004 Z4 for £4150 , all was well with car & price until the very honest seller explained he had been plaqued by random amber EML coming on . His non BMW garage read codes & suggested changing all 4 lambda probes at £380 total for job .
He went along with this after failing MOT on emission,s so expected to kill 2 birds with one invioce :oops:
Anyhow emission,s reading was MOt good & away he went without light , , , , ,, for 2 weeks then it returned :cry: so basically he was selling the car
"with no issues or faults" but he carried a code reader to clear the amber light as & when it re-appeared
Based on your history i just didn,t fancy the same carry on so passed on it
 
Just want to mention that to me it doesn't seem like the cat at fault anyway-pulls really well, no sulphur smell, passes emissions test.
 
Sounds like anO2 sensor not getting to temperature and reporting high levels of O2 in the exhaust but without the corresponding crank and cam acceleration errors that would be present to give high O2 the ecu reports it as a cat error. Would be a cheap fix if it is the O2
 
Nelly Welly said:
Sounds like anO2 sensor not getting to temperature and reporting high levels of O2 in the exhaust but without the corresponding crank and cam acceleration errors that would be present to give high O2 the ecu reports it as a cat error. Would be a cheap fix if it is the O2
Click to expand...
I have had pre and post 02 sensors replaced.
 
Manifold Air pressure ?

Can't see it being cat without smell or reduction of power.


What codes are being logged in the first trip as well as error log ?
 
Nelly Welly said:
Manifold Air pressure ?

Can't see it being cat without smell or reduction of power.


What codes are being logged in the first trip as well as error log ?
Click to expand...
Just the p0420 code
 
Ok strange but true. The ecu works by measuring the frequency of pulse required to maintain the sensors temperature and measuring the ratio of the number 1 sensor to the number 2 sensor. If they are different make to each other that could be a problem. If there is any exhaust leak around the sensor or cat this could also be the fault. If the cat is functioning try connecting An earth lead to the cat and the body of the vehicle as the chemical reaction can generate an earth loop current potentially Causing the error.
 
Thanks just to mention i have had a smoke test done for leaks and a software update to supposedly broaden the sesors range before tripping a fault.
 
I would def try another pair of sensors, the variance in them can cause many issues. In the short term a jump lead or similar from the body of the cat to a substantial earth may identify any earth loops on the sensor circuits.
 
Nelly Welly said:
I would def try another pair of sensors, the variance in them can cause many issues. In the short term a jump lead or similar from the body of the cat to a substantial earth may identify any earth loops on the sensor circuits.
Click to expand...
What would that do? If i put a wire from the body of the cat to a suitable earth should it trigger the light?
 
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