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How to Fix P0171?

Published on April 9th, 2022

P0171 is a generic error code that indicates that the fuel mixture in the engine is too lean. This can be caused by a variety of factors, including a dirty or faulty mass air flow sensor, a leak in the intake manifold, or a problem with the fuel injectors.

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1. Check and repair any leaks in the air intake system

  1. Check the air filter. If the filter is dirty or if it is missing, the air intake system will not work properly. Clean or replace the air filter.
  2. Check for obstructions in the air intake system. Blockages can cause air to not flow into the engine. Remove any obstructions and check the system again.
  3. Check for leaks in the air intake system. Leaks can cause air to leak into the engine. Check for leaks and fix them if necessary.
  4. Check for vacuum leaks. A vacuum leak can cause the air intake system to not work properly. Check for vacuum leaks and fix them if necessary.

2. Check the operation of the mass air flow sensor and replace it if necessary

  1. Disconnect the negative battery cable.
  2. Remove the screws that hold the air flow sensor in place.
  3. Pull the air flow sensor out of the engine.
  4. Inspect the sensor for damage. If the sensor is damaged, replace it.
  5. Install the new air flow sensor in the same way as the old one.
  6. Reconnect the negative battery cable.

3. Check the operation of the fuel injectors and clean or replace them if necessary

  1. Remove the air filter.
  2. Remove the fuel lines.
  3. Remove the fuel injectors.
  4. Clean the injectors.
  5. Reinstall the fuel lines and injectors.
  6. Test the engine.

Still not working? maybe try one of these options:

  1. Check the operation of the oxygen sensor and replace it if necessary.
  2. Check the engine compression and repair or replace the engine if necessary.