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Check engine codes


kevin kietzman

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Common Problems That Trigger the P0171 and P0174 Code


  • PCM software needs to be updated
  • Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.)
  • Mass Airflow Sensor (MAF)
  • Plugged Fuel Filter or weak Fuel Pump
  • Plugged or dirty Fuel Injectors

Common Misdiagnosis


  • Oxygen Sensors
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Just changing the air filter should not cause that issue. Modern cars have adaptive tuning, allowing the computer to optimize for changes in air density, temps, etc. I would start with re-seating all the fuel injector connectors and possibly cleaning the injectors. Spray the MAF with cleaner and clean the TB too.

 

How many miles on it? Any mods?

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Just changing the air filter should not cause that issue. Modern cars have adaptive tuning, allowing the computer to optimize for changes in air density, temps, etc. I would start with re-seating all the fuel injector connectors and possibly cleaning the injectors. Spray the MAF with cleaner and clean the TB too.

 

How many miles on it? Any mods?

Changing filters can indeed make your car throw codes. K&N even has a technical article about it and how to diagnose what is going on. They also advise you to call them for assistance if your car keeps throwing codes.

 

http://www.knfilters.com/check_engine_light.htm

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LOL.... the very first line on the site you linked says almost the exact same thing I did. "A properly installed K&N product should not cause the Service Light to illuminate."

 

I'm glad they have a self-service portal and customer service for their customer though. That's a plus.

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Do you really think they would come right out and say that it would throw codes? Tech articles are typically smoked over by a lawyer before they are posted and start off with disclaimers like that.

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Hi guys..I too am have the same issues..But i installed cmdp and gt500 TB and a JLT # 3 cal..with a bama tune..I cant keep the car running or I have a high idle at a stop and then it settles down only to go back up when i take off and i get codes p0171 & p0174..reloaded the tune and now its just the 174..I have no vac leaks and i check all hoses all's good there..I clear the codes and drive the car ..no check engine light... turn car off wait a few min's start the car and with in a min or so the codes come back...I'm going to call bama tune to send me a new tune and i'll see what happens then..Any thoughts on the problem.

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Cleaned the filter and mass flow sensor and havent had any more issues. My idle also was running high and all i did was was unhook the negative side of the battery for ten minuets and it is running great! thanks for all the replies..

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  • 3 weeks later...

my codes are worst.

 

P. 0010

0020

0102

1135

0141

0155

0161

0443

0446

 

The car sat for 8 years. last year it flooded just enough to get water onto the floor. otherwise it runs fine still. 11k miles. only.

 

Do you think it could be just a grounding issue OR perhaps the computer?

 

I changed all the 02's and still the 02's show up on the code reader.

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