P0173 Fault Code

Fuel Trim Malfunction (Bank 2)

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0173 code signifies a fuel trim malfunction specifically on bank 2 of the engine. This indicates that the engine control module (ECM) has detected that the fuel mixture in this bank is not within the acceptable range, leading to inefficient engine performance. Fuel trim refers to the adjustment made by the ECM to optimize the air-fuel mixture for combustion, which is crucial for engine efficiency and emissions control.

What are the symptoms of the P0173 code?

Common symptoms associated with a P0173 code may include:

• Poor engine performance, including rough idling or stalling.
• Increased fuel consumption and decreased fuel efficiency.
• Illuminated check engine light (CEL).
• Failed emissions test due to high emissions.
• Unusual odors of fuel or gasoline in the exhaust.

What causes the P0173 code?

Several factors can lead to a P0173 code, including:

• Vacuum leaks in the intake system affecting air intake measurement.
• Faulty or dirty mass airflow sensor (MAF) or manifold absolute pressure sensor (MAP).
• Leaking fuel injectors causing excess fuel delivery.
• Clogged fuel filter impeding fuel flow.
• Malfunctioning oxygen sensors providing incorrect feedback to the ECM.
• Issues with the fuel pressure regulator or fuel pump.

How to fix P0173?

To resolve a P0173 code, the following steps may be taken:

• Conduct a thorough diagnosis to identify the root cause of the malfunction.
• Inspect and repair any vacuum leaks in the intake system.
• Clean or replace the MAF and/or MAP sensors as necessary.
• Test and, if needed, replace leaking fuel injectors.
• Replace clogged fuel filters and check the fuel pump's functionality.
• Replace malfunctioning oxygen sensors and reset the ECM to monitor for future issues.