P0173 Code: Meaning, Symptoms, Causes & Fix

Overview

Code P0173 indicates a fault in Fuel Trim Malfunction (Bank 2), typically within fuel delivery and pressure control.

Symptoms

hesitation under acceleration
reduced fuel economy
hard starting

Common causes

Electrical fault in the affected circuit affecting fuel trim malfunction (bank 2)
Component failure in the monitored system
Connector pin damage/corrosion or harness stress near related components

How to diagnose P0173

Confirm P0173 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to fuel trim malfunction (bank 2) for obvious defects.
Use freeze-frame and live data to isolate whether the issue is electrical, mechanical, or control logic.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P0173

Low: This code is low to moderate severity in most cases, but diagnosis is still recommended to avoid recurring warnings.

Can you drive with P0173?

The vehicle is often drivable with P0173, but plan a repair window to prevent repeat faults.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (generic) in the fuel trim malfunction (bank 2) circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P0173 remains cleared under the conditions that originally set the code.

Fix options

Inspect circuit and connector condition.
Test component operation and replace if faulty.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$140-$550

Common mistakes when diagnosing P0173

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

P0173 in common vehicles

P0173 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P0173?

P0173 is commonly set by generic faults affecting fuel trim malfunction (bank 2).

How much does it cost to fix P0173?

For P0173, repair costs are typically $140-$550 depending on exact root cause, labor rates, and part quality.

Can I clear P0173 without repair?

You can clear P0173 temporarily, but the code usually returns until the underlying fault is corrected.