Trouble code P1407 indicates that the ECM detects insufficient or no exhaust gas recirculation (EGR) flow when the system commands EGR activation.
This code often appears together with other EGR system faults such as P1404 (EGR position range issue) or P1406 (EGR pintle position circuit or performance).
1. What P1407 Means
When the ECM commands EGR flow, it expects to see a drop in intake pressure or a change in airflow characteristics. If this doesn’t happen, the system assumes the EGR passage is blocked or the valve isn’t opening.
The EGR system is a key component in NOx control. More about EGR emission role can be found at the EPA’s technical overview: EPA Emissions Reference.
2. Common Symptoms
- Check Engine Light on
- Rough idle (especially when warm)
- Poor fuel efficiency
- Ping/knock under load
- Higher engine temps during highway cruising
3. Likely Causes of P1407
- Carbon blockage in EGR passages
- EGR valve not opening fully
- Faulty EGR control solenoid
- Disconnected/broken vacuum line (on vacuum-type EGR)
- Low system voltage affecting EGR actuator response
- Faulty DPFE/MAP sensor not detecting changes
4. How Professional Techs Diagnose P1407
Step 1 — Scan the System for Live Data
A system-level scan is essential. With the iCarsoft CR Ultra P, you can view:
- Commanded EGR vs. Actual EGR flow
- Intake MAP pressure changes
- DPFE sensor voltage
- Related codes such as P0401, P1404, P1406
Step 2 — Physical Inspection
- Check if the valve moves freely when removed
- Inspect carbon buildup in the intake runners
- Verify vacuum line integrity (if applicable)
Step 3 — Test EGR Actuator
Using bidirectional controls, command the EGR valve to open/close. If commanded changes don’t produce airflow changes, the valve may be sticking.
Step 4 — Check Sensors
- Verify MAP sensor reacts when EGR opens
- Check DPFE hoses for melting/blockage
- Verify electrical resistance matches OE specs
Step 5 — Clean or Replace Components
Many P1407 cases are simply heavy carbon buildup inside the intake and EGR channels.
5. Recommended Scan Tool: CR Ultra P
For EGR flow diagnostics, the CR Ultra P offers:
- Bidirectional EGR functional tests
- Real-time MAP/DPFE data
- Full-system diagnostics across all major modules
- Touchscreen interface + WiFi lifetime updates
- 4.0 series coverage + two extra OEM brands included
- Shipping available for U.S. and U.K. customers
Need support? Contact us via the chat box or email service@icarsoft-us.com.
6. FAQ — P1407 Quick Answers
Q1. Is P1407 usually caused by carbon buildup?
Yes. Blocked EGR passages are by far the most common failure point.
Q2. Can a faulty MAP or DPFE sensor trigger P1407?
Absolutely. If the ECM cannot detect airflow change, it assumes there is “no flow.”
Q3. Should I clean or replace the EGR valve?
Start with cleaning. If the pintle doesn’t move smoothly afterward, replacement is recommended.
Q4. Does the CR Ultra P support EGR activation testing?
Yes, it can command open/close tests, which is required for proper diagnosis.
Q5. Can P1407 cause long-term engine damage?
Extended no-flow conditions increase NOx emissions and may lead to knock or overheating on long highway runs.
7. Summary
P1407 typically indicates restricted EGR flow or a sensor unable to verify flow change. With proper scanning and inspection, the root cause can be found quickly.
