P1423 Code: Meaning, Symptoms, Causes & Fix

Overview

Symptoms

• reduced performance
• increased fuel use
• check engine light

Common causes

• Control module logic or calibration issue affecting egi functionality test failed
• Component failure in the monitored system
• Connector pin damage/corrosion or harness stress near related components

How to diagnose P1423

1. Confirm P1423 and capture freeze-frame data with a professional scan tool.
2. Inspect wiring, connectors, and grounds related to egi functionality test failed for obvious defects.
3. Use freeze-frame and live data to isolate whether the issue is electrical, mechanical, or control logic.
4. Check for related DTCs to identify the root-cause chain before replacing parts.
5. After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P1423

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

Can you drive with P1423?

The vehicle is often drivable with P1423, 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)

1. Repair obvious wiring/connector faults first to prevent repeat parts replacement.
2. Address the root fault mode (generic) in the egi functionality test failed circuit/system.
3. Apply the required relearn/adaptation procedure if specified by service information.
4. Road-test and verify P1423 remains cleared under the conditions that originally set the code.

Fix options

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

Typical repair cost

$100-$450

Common mistakes when diagnosing P1423

• 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.

P1423 in common vehicles

P1423 appears across makes such as BMW, Mercedes-Benz, Audi, Volvo. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P1423?

P1423 is commonly set by generic faults affecting egi functionality test failed.

How much does it cost to fix P1423?

For P1423, repair costs are typically $100-$450 depending on exact root cause, labor rates, and part quality.

Can I clear P1423 without repair?

You can clear P1423 temporarily, but the code usually returns until the underlying fault is corrected.

Helpful tools

• Estimate repair cost
• Decode your VIN
• Calculate fuel cost