P1407 – Exhaust Gas Recirculation (EGR) System Low Flow Detected

You just got home and see that the Check Engine Light is on. Not what you needed. You scan the code and boom - P1407. The first question? "Is my car about to betray me?"

Before the panic sets in, here's the quick clarity you actually need: OBD code P1407 refers to "EGR System Low Flow Detected," meaning your engine isn't getting the amount of recirculated exhaust gas it expects.

This guide explains what engine code P1407 means for your EGR system, common symptoms, causes, repair options, and prevention tips. We also cover diagnostics, step-by-step fixes, affected vehicles, and FAQs.

What Does P1407 Mean?

P1407 = EGR No Flow or "EGR System Low Flow Detected." Depending on the manufacturer, the exact wording differs, but the heart of the issue is the same: Your Exhaust Gas Recirculation (EGR) system isn't allowing the correct amount of exhaust gas to circulate back into the engine.

How the Code Is Triggered

Your car's PCM/ECM monitors the EGR system through sensors and flow feedback. If it notices that the amount of exhaust gas entering the intake is lower than expected, the PCM logs DTC P1407. In most cars, the PCM waits for multiple consecutive "failed" EGR flow tests before turning on the CEL - so the issue is usually real, not a one-time glitch.

Why the EGR System Matters

The EGR's job is to reduce emissions and control combustion temperatures. When flow drops, your engine can run hotter, detonate, idle badly, or waste fuel. Over time, issues like carbon buildup can cause long-term performance losses.

Common Symptoms of P1407

When trouble code P1407 shows up, here are the symptoms drivers most often notice:

• Check Engine Light ON — always the #1 giveaway.
• Rough idle — the engine feels unstable.
• Reduced power — especially during acceleration.
• Poor fuel economy — extra trips to the pump.
• Hard starts — the engine hesitates before firing.
• Failed emissions test — common with low EGR flow.
• Increased engine temperature — mild but noticeable.

Severity Level

• Mild: CEL on with no major drivability problems.
• Moderate: Hesitation, rough idle, and poor mileage.
• Severe: Possible overheating, misfires, or stalling if ignored.

Possible Causes of P1407

Here's the full list of everything that can trigger OBD code P1407:

1. Carbon-Clogged EGR Valve

Carbon deposits physically block exhaust flow, making the PCM detect low EGR movement.

2. Clogged EGR Ports or Passages

Even if the valve works, blocked passages choke the system.

3. Faulty EGR Valve Position Sensor

If the sensor misreports valve position, the PCM thinks flow is low.

4. Defective EGR Solenoid or Control Circuit

If the solenoid fails, it can't open the valve properly.

5. Vacuum Line Leaks (Older Engines)

Vacuum-controlled EGR valves depend heavily on perfect vacuum pressure.

6. Wiring Problems (Shorts, Opens, Corrosion)

Any break in the EGR circuit causes incorrect data.

7. Failed DPFE Sensor (Ford & Mazda Models)

Ford especially uses DPFE to measure EGR pressure — when this fails, Ford code P1407 pops up.

8. Faulty EGR Temperature Sensor (Toyota, Lexus)

If the temp doesn't rise during EGR flow, the ECM assumes blockage.

9. PCM Software Issues

Rare, but certain models require PCM updates.

How to Diagnose P1407

P1407 popped up. Not sure what it means. Maybe check a few things before calling a mechanic or grabbing a wrench. This will help you understand what exactly is going on!

Tools Needed

• OBD-II Scanner
• Basic socket set
• Multimeter
• Vacuum gauge (if applicable)
• Carb/EGR cleaner
• Smoke machine (optional, for pro-level leak detection)

Step 1: Confirm the Code

Scan for engine code P1407 and note any related codes like P0401, P1406, P0404, etc.

Step 2: Inspect the EGR Valve

Check for carbon buildup, stuck pintle, or visible blockage.

Step 3: Test EGR Operation

• Electric EGR: Activate via scan tool.
• Vacuum EGR: Apply vacuum manually and watch for engine RPM drop.

Step 4: Check EGR Passages

Remove the throttle body or intake runners (vehicle dependent) and inspect ports.

Step 5: Inspect DPFE or EGR Temp Sensor

• Measure voltage.
• Check for melted hoses (especially on older Fords).

Step 6: Look for Vacuum Leaks

Use smoke machine or carb cleaner around suspected areas.

Step 7: Electrical Testing

Multimeter check: resistance, continuity, grounds, and 12V supply.

Step 8: PCM Software & Updates

Search technical service bulletins (TSBs) for model-specific instructions.

If you want to explore other engine codes beyond P1407, check out SuncentAuto's complete OBD-II codes list.

Repair Solutions for P1407

Once you've confirmed DTC P1407, the next step is figuring out which repair actually solves the problem — without replacing half the engine.

1. Clean the EGR Valve (Most Common Fix)

Carbon buildup is the #1 cause. Cleaning restores normal flow.

2. Clean EGR Passages / Ports

Some Hondas and Toyotas need intake manifold cleaning.

3. Replace Faulty EGR Valve

If stuck or electrically dead, replacement is the only fix.

4. Replace DPFE Sensor (Ford, Mazda)

A notorious failure point for these vehicles.

5. Replace EGR Temperature Sensor

Often needed in Toyota/Lexus.

6. Fix Vacuum Leaks

Replace hoses, clamps, or connectors.

7. Fix Wiring Issues

Corroded plugs or cracked wires can cause false flow readings.

8. PCM Reflash

Some vehicles require updated EGR logic to prevent false P1407 readings.

For long-term reliability, consider SuncentAuto EGR Delete Kits. Removing the EGR system allows cleaner intake airflow, reduces carbon buildup, and helps prevent repeat EGR failures.

Vehicles Commonly Affected by P1407

Some makes and models are more prone to P1407 due to EGR design, sensor types, or carbon buildup tendencies. Understanding which vehicles are commonly affected helps you anticipate potential issues and costs.

Repair Cost Estimate for P1407

Knowing potential costs upfront helps drivers plan repairs for DTC P1407 efficiently. Repair costs vary based on the vehicle model, year, and severity of the issue. Here’s a breakdown of typical costs for diagnosis and fixes:

Factors affecting cost: vehicle make/model/year, labour rates, parts availability, and complexity.

Prevention Tips for P1407

Preventing code P1407 is much easier and cheaper than repairing it. Here are actionable tips every driver can follow to maintain proper EGR system flow and avoid recurring trouble codes:

1. Clean EGR Valve Regularly

Prevents carbon buildup, the #1 cause of trouble code P1407.

2. Use High-Quality Fuel

Low-quality fuel increases deposits that clog passages.

3. Replace Air Filters on Time

Keeps air clean and reduces soot formation.

4. Fix Vacuum Leaks Early

A tiny leak today becomes a full-blown EGR failure later.

5. Periodic Intake Cleaning

Use cleaners every 10,000–15,000 miles.

6. Follow Manufacturer Maintenance Guide

Factory intervals are designed to prevent codes like DTC P1407.

7. Inspect Wiring During Service

Prevents sensor-related false triggers.

8. Monitor Engine Performance

Early detection of rough idle or reduced power can prevent costly repairs.

FAQs About P1407

Conclusion

Addressing engine code P1407 promptly can save drivers from costly repairs and prevent long-term engine damage. Regular maintenance, including EGR cleaning, sensor checks, and timely intake inspection, ensures proper exhaust gas flow and keeps your vehicle running efficiently.

Using high-quality fuel and monitoring engine performance helps prevent this trouble code from recurring. Drivers should consider consulting a professional technician for proper diagnosis. For long-term prevention, consider the SuncentAuto EGR delete kits to prevent all EGR-related trouble codes from occurring.

Save this guide for future reference and prioritize proactive maintenance to avoid unexpected DTC P1407 issues and keep your engine performing reliably.