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Steve
Steve, BMW Expert
Category: BMW
Satisfied Customers: 24187
Experience:  BMW Expert
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my car is consuming high petrol engine management light appeared

Resolved Question:

my car is consuming high petrol
engine management light appeared i did the diagnostic test it revealed two fault codes
p0171 system too lean bank 1
p0174 ystem too lean bank 2
i took it to a mechanic they said it's the faulty catalytic converter causing high fuel consumption and needs replacing, and quoted me £600 parts labour.

can i trust them on what they are saying.
Submitted: 3 years ago.
Category: BMW
Expert:  Steve replied 3 years ago.
Do you know what testing has been carried out?
Customer: replied 3 years ago.
He just sprayed into the engine and that was it. It took about 10 mins to come to a conclusion
Expert:  Steve replied 3 years ago.

he sprayed something into the engine?

 

Customer: replied 3 years ago.
Yes
Expert:  Steve replied 3 years ago.

I would not trust this diagnosis

 

the codes you have are not usually associated with a failed cat, and a failed cat is not a common cause of high fuel consumption

 

to verify a bad cat, significantly more diagnostics would need to be carried out

 

you absolutely need to seek a second opinion.

 

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 3 years ago.
Ok what are the symptoms of a failed cat
Expert:  Steve replied 3 years ago.

codes related to catalytic efficiency

 

foul odor

 

rattling noise

 

high exhaust back pressure

 

poor emissions quality as measured live with a high end diagnostic computer

 

Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you.

Customer: replied 3 years ago.
In your opinion what could be the fault, just a indication
Expert:  Steve replied 3 years ago.

the most common things that would cause high fuel consumption would be a failed airflow sensor, failed temp sensor, failed 2 sensor or possibly a simple maintence issue like plugs or air filter

 

the most common causes of the codes you have are an air leak, failed airflow sensor or failed crankcase ventvalve

 

there is detailed testing and live reading/measurements that can be taken to verify for small 1 hour diagnostic investment

 

Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

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