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P0171 ACURA

P0171 ACURA - Fuel Injection System Too Lean Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Intake air leaks
  • Faulty front heated oxygen sensor
  • Ignition misfiring
  • Faulty fuel injectors
  • Exhaust gas leaks
  • Incorrect fuel pressure
  • Lack of fuel
  • Faulty Mass Air Flow (MAF) sensor
  • Incorrect Positive Crankcase Ventilation (PCV) hose connection

Tech notes

If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.

There is a factory service bulletin for the following Acura models:

2007 Acura TL Type–S
2008 Acura TL Type–S
2007-2008 Acura TL P0171 OBDII Code

When is the code detected?

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Excessive Fuel Consumption

P0171 Acura Description

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.

In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the Malfunction Indicator Light (MIL) (2 trip detection logic).

OBDII Code P0171 Acura - Fuel Injection System Too Lean Bank 1 - AutoCodes.com

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