P0402 Code: Meaning, Symptoms, Causes & Fix

Overview

Symptoms

• rough operation in certain conditions
• check engine light
• increased fuel use

Common causes

• Sensor output out of expected lower range affecting exhaust gas recirculation flow excessive detected
• High circuit resistance
• Connector pin damage/corrosion or harness stress near related components

How to diagnose P0402

1. Confirm P0402 and capture freeze-frame data with a professional scan tool.
2. Inspect wiring, connectors, and grounds related to exhaust gas recirculation flow excessive detected for obvious defects.
3. Compare live data against expected lower threshold and verify ground/reference circuits.
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 P0402

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P0402?

Most vehicles can be driven short-term with P0402, but postpone heavy load/highway driving until repaired.

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 (low) in the exhaust gas recirculation flow excessive detected circuit/system.
3. Apply the required relearn/adaptation procedure if specified by service information.
4. Road-test and verify P0402 remains cleared under the conditions that originally set the code.

Fix options

• Replace failed sensor if signal remains low.
• Repair connector resistance issues.
• Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$200-$900

Common mistakes when diagnosing P0402

• 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.

P0402 in common vehicles

P0402 appears across makes such as Nissan, Hyundai, Kia, Volkswagen. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P0402?

P0402 is commonly set by low faults affecting exhaust gas recirculation flow excessive detected.

How much does it cost to fix P0402?

For P0402, repair costs are typically $200-$900 depending on exact root cause, labor rates, and part quality.

Can I clear P0402 without repair?

You can clear P0402 temporarily, but the code usually returns until the underlying fault is corrected.

Helpful tools

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