P0404 Code: Meaning, Symptoms, Causes & Fix

Overview

Code P0404 indicates a fault in Exhaust Gas Recirculation Circuit Range/Performance, typically within powertrain controls.

Symptoms

increased fuel use
reduced performance
rough operation in certain conditions

Common causes

Component out of calibration affecting exhaust gas recirculation circuit range/performance
Sensor drift or delayed actuation
Connector pin damage/corrosion or harness stress near related components

How to diagnose P0404

Confirm P0404 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to exhaust gas recirculation circuit range/performance for obvious defects.
Compare commanded vs actual values in live data under the same operating condition.
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 P0404

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

Can you drive with P0404?

Most vehicles can be driven short-term with P0404, 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)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (performance) in the exhaust gas recirculation circuit range/performance circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P0404 remains cleared under the conditions that originally set the code.

Fix options

Test component operation against service specs.
Replace out-of-range component and verify live data.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$200-$900

Common mistakes when diagnosing P0404

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.

P0404 in common vehicles

P0404 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 P0404?

P0404 is commonly set by performance faults affecting exhaust gas recirculation circuit range/performance.

How much does it cost to fix P0404?

For P0404, repair costs are typically $200-$900 depending on exact root cause, labor rates, and part quality.

Can I clear P0404 without repair?

You can clear P0404 temporarily, but the code usually returns until the underlying fault is corrected.