Check engine error codes P0170 and P0173

Tiny
JACKDOIT
  • MEMBER
  • 2006 MERCEDES BENZ C230
  • 2.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 230,000 MILES
Every year after hot summer days, in November and December I have the same problem. After 200 km check engine light is on and there is p0170 and p0173 code. Vacuum leaks is all okay, o2 sensors is okay, fuel pump is okay. What to do? Please help give me solution. Thank You
Friday, December 9th, 2016 AT 2:40 PM

10 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,470 POSTS
A common issue on Mercedes that set those codes is a defective Mass Airflow Sensor. You would need to connect a scan tool and look at the airflow the MAF is reporting to make sure. At idle you should see between 3.5 - 4.5 grams per second and between 8 and 12 g/s at 2500 no load rpm. Be careful of the lower cost replacements, very often they are out of spec as well.
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Friday, December 9th, 2016 AT 9:42 PM
Tiny
JACKDOIT
  • MEMBER
  • 6 POSTS
Thank You. But car is running normally, there is no any change in the vehicle work, only codes.
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Saturday, December 10th, 2016 AT 12:34 AM
Tiny
STEVE W.
  • MECHANIC
  • 14,470 POSTS
Mercedes is one of the few companies that use those codes. They show that the ECM is pushing the fuel trim controls over the range they are supposed to operate in. They use a very narrow range compared to other makes. You may not notice the minor change in mileage they cause or other minute changes. However the computer sees them and sets those codes. The only real way to find the problem is to watch the numbers live.
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Saturday, December 10th, 2016 AT 8:00 AM
Tiny
JACKDOIT
  • MEMBER
  • 6 POSTS
Thank You for answer! Experts say different things o2 sensor, fuel pump, fuel filter, Maf, inject, other say nothing do not worry it is dirty fuel problem, just add 100 ml 96% medical alcohol. Who to believe? I want to know what the exact problem. I do not trust anyone. Now put my pictures, I do not know what they mean, I captured when the car is off, something they say.
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Saturday, December 10th, 2016 AT 9:53 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,440 POSTS
Hey JACKDOIT,

My wife has this car and I just went through a whole ordeal with a code that involved the intake camshaft problem, the bottom line is the car had a boot between the mass air flow sensor and the blower which I replaced. The codes kept coming up, I finally figured out that the adaptation of the computer needed to be cleared so the computer could "relearn" the engine again, have not had a problem since.

This cannot be done with a normal scanner and must be done with the mercedes tool with the appropriate program.

Please let us know happens so it will help others.

Best, Ken
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Monday, December 12th, 2016 AT 1:07 PM
Tiny
JACKDOIT
  • MEMBER
  • 6 POSTS
Hey Ken. Thank You!
I still have not solved the problem, I think it's all about Maf sensor, but there is no one simptoms about faulty MAF
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Monday, December 12th, 2016 AT 2:08 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,440 POSTS
Yep, if the MAF is not reading correctly it will cause problems but may not be enough to trigger a check engine light.

I wish you were close I have one right here you could try :)

Let us know.

Best, Ken
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Monday, December 12th, 2016 AT 3:17 PM
Tiny
JACKDOIT
  • MEMBER
  • 6 POSTS
Hey friends ! The problem was solved. The reason was related to Intake Manifold Runner control flap.I saw with my own eyes, there is broken air flap repair kit.
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Friday, December 16th, 2016 AT 4:41 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,440 POSTS
Nice work Jack! Glad you could get the problem fixed. Please use 2Carpros anytime we are here to help and tell a friend!

Happy Holidays!
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Friday, December 16th, 2016 AT 10:52 AM
Tiny
JACKDOIT
  • MEMBER
  • 6 POSTS
Thank You !
Happy Holidays ))))
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Saturday, December 17th, 2016 AT 2:43 AM

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