Exhaust Gas Recirculation Control Circuit Range/Performance
P0404 means Exhaust Gas Recirculation Control Circuit Range/Performance. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.
What you may notice
Symptoms
- 01Check Engine light
- 02Failed emissions inspection
- 03Possible rough idle, odor, or reduced fuel economy
- 04Often little or no noticeable drivability change
Where to look first
Common causes
- 01Blocked, leaking, or stuck emissions-control passage or valve
- 02Vacuum hose, exhaust leak, or plumbing problem
- 03Faulty pressure, position, oxygen, or flow sensor
- 04Wiring, connector, solenoid, relay, or control fault
A sensible sequence
Best diagnostic order
- 01Record codes, freeze-frame data, and readiness-monitor status
- 02Inspect the complete system for disconnected hoses, leaks, damage, or carbon blockage
- 03Test the actuator and its electrical circuit
- 04Compare command, feedback, oxygen-sensor response, and fuel trims
- 05Complete the appropriate drive cycle and verify that the monitor passes
Step by step
What to check and repair
- 01Inspect hoses, pipes, valves, connectors, and related fuses
- 02Command the system with a scan tool where supported
- 03Check sensor response and verify that flow actually changes
- 04Repair leaks or restrictions before replacing major components
Read the signals
Live-data clues
System command and feedback
- Typical behavior
- Feedback should respond when the control module commands the system
- Possible clue
- No response can indicate a blocked passage, failed actuator, sensor, or circuit
Oxygen-sensor and fuel-trim response
- Typical behavior
- Values should react predictably during a controlled system test
- Possible clue
- The response helps confirm whether gas or vapor flow actually changed
| Parameter | Typical behavior | What it can suggest |
|---|---|---|
| System command and feedback | Feedback should respond when the control module commands the system | No response can indicate a blocked passage, failed actuator, sensor, or circuit |
| Oxygen-sensor and fuel-trim response | Values should react predictably during a controlled system test | The response helps confirm whether gas or vapor flow actually changed |
What P0404 means
P0404 is a generic powertrain diagnostic trouble code defined as “Exhaust Gas Recirculation Control Circuit Range/Performance.” The vehicle control module stored it after the monitored circuit or system failed its expected test. The code identifies the area and failure type; it does not by itself prove that one named component must be replaced.
Diagnostic direction
Emissions codes often require a functional test, not just a resistance check. Confirm that the commanded valve or pump changes real flow and produces the expected sensor response.
Before clearing the code
Save stored, pending, and permanent codes plus freeze-frame data. Note the operating condition that set the code, inspect related connectors and wiring, and check vehicle-specific service information. After a verified repair, clear the code only when appropriate and repeat the enabling conditions to confirm that it does not return.