Diagnostic trouble code P1404 indicates an issue with the EGR valve position sensor range or performance. The PCM detects that the EGR valve position does not match the expected signal during operation.
This code often appears along with other EGR-related faults such as P1400 or P1406. If needed, you can also refer to our related guide: P1400 code basics.
1. What P1404 Actually Means
P1404 is normally triggered when the PCM senses that the EGR pintle position is either:
- Not fully closed when it should be closed
- Out of the expected voltage range
- Responding slower than commanded
The EGR system's primary function is to reduce NOx emissions. For background reference, the U.S. EPA outlines this here: EPA Emissions Overview.
2. Common Symptoms
- Check Engine Light illuminated
- Rough or unstable idle
- Hesitation when accelerating
- Poor fuel economy
- Intermittent stalling in severe cases
3. Possible Causes
- Carbon buildup preventing full EGR closure
- EGR valve stuck partially open
- Faulty EGR position sensor
- Worn or sticking EGR pintle
- Damaged wiring or poor ground connection
- Low system voltage affecting sensor feedback
4. Step-by-Step Diagnosis (Technician Workflow)
Step 1 — Scan the System
Use a professional scanner with live data functions. The iCarsoft CR Ultra P can view:
- EGR commanded vs actual feedback
- Sensor voltage output
- EGR actuator response time
- Linked emissions codes
Step 2 — Inspect the EGR Valve
- Remove and inspect for carbon obstruction
- Check pintle movement manually
- Ensure the valve can close completely
Step 3 — Check Wiring & Ground Points
- Look for pin corrosion or bent terminals
- Verify 5V reference and ground continuity
- Check for high resistance in sensor circuits
Step 4 — Test EGR Position Sensor
Compare voltage readings to OE specifications. If the feedback signal jumps or stays flat, replace the sensor or entire module depending on design.
Step 5 — Relearn & Clear Codes
After repairs, use the CR Ultra P to clear codes and verify the EGR closes properly during idle and decel.
5. Recommended Diagnostic Tool — iCarsoft CR Ultra P
The CR Ultra P is ideal for resolving EGR position issues thanks to:
- Bidirectional tests (EGR open/close command)
- Full-system diagnostics with OE-level detail
- Lifetime WiFi updates
- Touchscreen interface
- Supports all 4.0-series coverage + two extra brands
- Ships to both U.S. and UK customers
Have questions? Contact our support team via the online chat box or email service@icarsoft-us.com.
6. FAQ — P1404 Quick Answers
Q1. Does carbon buildup cause P1404 most of the time?
Yes. A sticking pintle or partially open EGR is the most common root cause.
Q2. Can a weak battery trigger P1404?
Low system voltage can affect sensor feedback and cause a false triggering.
Q3. Should the EGR be replaced or cleaned?
If the valve physically sticks, cleaning may restore proper movement. If the position sensor is faulty, replacement is recommended.
Q4. Can the iCarsoft CR Ultra P command the EGR valve?
Yes, it supports bidirectional EGR activation tests for most manufacturers.
Q5. How soon will the code return after clearing?
If the EGR cannot close fully, the code often returns within one or two drive cycles.
7. Summary
P1404 usually points to a sticking EGR valve or incorrect position sensor feedback. A proper scan and mechanical inspection help isolate the cause quickly. The CR Ultra P provides the live data and actuator tests needed for accurate diagnosis.
