Check engine light or malfunction indicator lamp is on

[XEvolutioNX]

Check engine light come on for my dad 2008 E class error code are below (from workshop uncle)

P0171 system too lean bank 1

P0174 system too lean bank 2

P0420 catalyst system efficiency below threshold bank 1

P0430 catalyst system efficiency below threshold bank 2

Workshop uncle recommended for a catalytic converter replacement first which cost around $2k instead of  O2/Mass air flow sensor sensor replacement. 

Is it really a clogged catalytic converter causing the CEL or just faulty O2/MAF sensor.

Any recommendations for good workshop that I can visit for second opinion..

Car Mileage 210k

 

Edited May 3, 2022 by XEvolutioNX

[Ct3833]

P0171 and p0174 Could be due to many reasons such as fuel pump,  fuel sensor , filter, dirty injector head etc. 

[Mkl22]

6 hours ago, XEvolutioNX said:

Check engine light come on for my dad 2008 E class error code are below (from workshop uncle)

P0171 system too lean bank 1

P0174 system too lean bank 2

P0420 catalyst system efficiency below threshold bank 1

P0430 catalyst system efficiency below threshold bank 2

Workshop uncle recommended for a catalytic converter replacement first which cost around $2k instead of  O2/Mass air flow sensor sensor replacement. 

Is it really a clogged catalytic converter causing the CEL or just faulty O2/MAF sensor.

Any recommendations for good workshop that I can visit for second opinion..

Car Mileage 210k

 

Code 171 and 174 are the upstream o2 sensors before the cat. For both to fail together is quite rare. Same with 420 and 430 which are the o2 after the cat. 
super rare for all 4 to fail. Or for both cats to fail at the same time. 
I think we should be looking at a different problem. Quite sure it has nothing to do with the cat. 

which workshop is this? 
your car should be a w211 e230 2.5 v6 right, since there is bank1 and bank2. 
 

you can try the following workshops, in no order of preference. 

chip soon at tampines, auto spritze at Kim Chuan, MB auto at amk auto point. They all have the MB diagnostic tool. 

Edited May 4, 2022 by Mkl22

[Watwheels]

Got try to Google the car make year and model with these codes?

You cannot trust mechanics who read directly from the fault codes and start changing parts according to it.

Sometimes when I forget to plug back in my MAF after cleaning the engine throttle body and air intake manifold. It will kick up extra error codes like even my safety sensing also got error. I cant be sending my car to change out and replace all these parts.

[Watwheels]

11 hours ago, XEvolutioNX said:

Check engine light come on for my dad 2008 E class error code are below (from workshop uncle)

P0171 system too lean bank 1

P0174 system too lean bank 2

P0420 catalyst system efficiency below threshold bank 1

P0430 catalyst system efficiency below threshold bank 2

Workshop uncle recommended for a catalytic converter replacement first which cost around $2k instead of  O2/Mass air flow sensor sensor replacement. 

Is it really a clogged catalytic converter causing the CEL or just faulty O2/MAF sensor.

Any recommendations for good workshop that I can visit for second opinion..

Car Mileage 210k

 

Read the first couple of error codes first. See what it is about. I Googled the first error code and this result came back.

P0171 - System Too Lean (Bank 1) means that the engine air-fuel mixture is too lean, or there is too much air and too little fuel. Driving a car with the code P0171 can cause more damage to the engine over time, as when the engine runs lean, the combustion temperature is higher.

P0171 MERCEDES-BENZ code possible causes

Intake air leaks

Faulty Mass Air Flow (MAF) sensor

Faulty front heated oxygen sensor Ignition misfiring

Faulty fuel injectors

Exhaust gas leaks

Incorrect fuel pressure Lack of fuel

Incorrect Positive Crankcase Ventilation (PCV) hose connection

 

The mechanic should check for hose leaks or exhaust leaks first, They should have tools to check the MAF sensor. Check fuel injectors to see whether they are clogged with carbon. Whatever is going on here is affecting the backend which is the exhaust end or the cat converter. Too much oxygen is detected in the exhaust which might throw out the cat error codes.

Nobody check from the bottom or choose the most expensive part and tell the owner to change that. Avoid going to this mechanic and find anther honest workshop. Preferrably workshops that do mercs. They should have dedicated OBD diagnotic tool for mercs which will show more accurate error codes.
 

[Jamesc]

Always change the cheapest and easiest thing first

[Mkl22]

1 hour ago, Watwheels said:

Read the first couple of error codes first. See what it is about. I Googled the first error code and this result came back.

P0171 - System Too Lean (Bank 1) means that the engine air-fuel mixture is too lean, or there is too much air and too little fuel. Driving a car with the code P0171 can cause more damage to the engine over time, as when the engine runs lean, the combustion temperature is higher.

P0171 MERCEDES-BENZ code possible causes

Intake air leaks

Faulty Mass Air Flow (MAF) sensor

Faulty front heated oxygen sensor Ignition misfiring

Faulty fuel injectors

Exhaust gas leaks

Incorrect fuel pressure Lack of fuel

Incorrect Positive Crankcase Ventilation (PCV) hose connection

 

The mechanic should check for hose leaks or exhaust leaks first, They should have tools to check the MAF sensor. Check fuel injectors to see whether they are clogged with carbon. Whatever is going on here is affecting the backend which is the exhaust end or the cat converter. Too much oxygen is detected in the exhaust which might throw out the cat error codes.

Nobody check from the bottom or choose the most expensive part and tell the owner to change that. Avoid going to this mechanic and find anther honest workshop. Preferrably workshops that do mercs. They should have dedicated OBD diagnotic tool for mercs which will show more accurate error codes.
 

Maybe workshop wanna ketok the dad! Now the son ask for 2nd opinion, then the plans are dashed! 

But yes. Always the cheap and simple solutions 1st. I suspect a vacuum leak somewhere. But with a merc star tool this can be easily found. 

[XEvolutioNX]

13 hours ago, Ct3833 said:

P0171 and p0174 Could be due to many reasons such as fuel pump,  fuel sensor , filter, dirty injector head etc. 

Thanks for the information, will look into in when at workshop 😊

[XEvolutioNX]

9 hours ago, Mkl22 said:

Code 171 and 174 are the upstream o2 sensors before the cat. For both to fail together is quite rare. Same with 420 and 430 which are the o2 after the cat. 
super rare for all 4 to fail. Or for both cats to fail at the same time. 
I think we should be looking at a different problem. Quite sure it has nothing to do with the cat. 

which workshop is this? 
your car should be a w211 e230 2.5 v6 right, since there is bank1 and bank2. 
 

you can try the following workshops, in no order of preference. 

chip soon at tampines, auto spritze at Kim Chuan, MB auto at amk auto point. They all have the MB diagnostic tool. 

The workshop is located at Yishun industrial park (can’t mention name here).

yeap it’s a W211 E230

Thanks for the workshop recommendations

[mersaylee]

4 hours ago, Jamesc said:

Always change the cheapest and easiest thing first

Some find it easier to change car than change tyre when worn or battery when flat...😁

[Ct3833]

11 hours ago, Mkl22 said:

Code 171 and 174 are the upstream o2 sensors before the cat. For both to fail together is quite rare. Same with 420 and 430 which are the o2 after the cat. 
super rare for all 4 to fail. Or for both cats to fail at the same time. 
I think we should be looking at a different problem. Quite sure it has nothing to do with the cat. 

which workshop is this? 
your car should be a w211 e230 2.5 v6 right, since there is bank1 and bank2. 
 

you can try the following workshops, in no order of preference. 

chip soon at tampines, auto spritze at Kim Chuan, MB auto at amk auto point. They all have the MB diagnostic tool. 

certainly a  W211 but could be a E200 too, for 4 cylinder layout, Bank 1 refers to cylinder 1 and 2 and bank 2 refers to 3 and 4. saw this somewhere. 

[Mkl22]

1 hour ago, Ct3833 said:

certainly a  W211 but could be a E200 too, for 4 cylinder layout, Bank 1 refers to cylinder 1 and 2 and bank 2 refers to 3 and 4. saw this somewhere. 

https://mechanicbase.com/troubleshooting/bank1-vs-bank2/

[Gnahp]

1 hour ago, Ct3833 said:

certainly a  W211 but could be a E200 too, for 4 cylinder layout, Bank 1 refers to cylinder 1 and 2 and bank 2 refers to 3 and 4. saw this somewhere. 

flat 4 eingine?

[toccarakinder98]

You can check IT here to see if it can be solved