P1401 – Exhaust Flap Control Circuit Range/Performance (some manufacturers)

What is the P1401 Code and How Urgent is It?

The P1401 code indicates a problem with the Differential Pressure Feedback EGR (DPFE) sensor circuit. This code means the powertrain control module (PCM) has detected the DPFE sensor signal voltage is above the expected range.

Urgency: If you get a P1401 code, STOP DRIVING immediately and have your vehicle repaired. Driving with a malfunctioning EGR system can lead to poor engine performance, increased emissions, and potential engine damage.

Is P1401 Make-Specific?

While the P1401 code is most commonly associated with Ford vehicles from the late 1990s through the 2000s, it can apply to any vehicle equipped with a DPFE-type EGR system. However, the exact troubleshooting steps and part numbers may vary between makes and models.

Parts Involved and Their Role

The main components related to a P1401 code are:

1. DPFE Sensor: Monitors pressure changes to determine EGR flow and sends a signal to the PCM. It has two hoses connected to the EGR tube near the valve.

2. EGR Valve: Allows metered amounts of exhaust gas to enter the intake manifold to lower combustion temperatures and reduce NOx emissions.

3. EGR Tube: Connects the exhaust manifold to the intake, with metal hoses linking to the DPFE sensor to measure pressure differentials.

Common Causes

Potential causes of a P1401 code include:

• Faulty DPFE sensor (most common)
• Damaged or blocked vacuum hoses to the DPFE sensor
• Stuck open EGR valve
• Plugged EGR passages or tube
• Leaks in the intake manifold
• Electrical short or open in the DPFE circuit
• Failed PCM (rare)

Diagnostic Steps

1. Visually inspect the DPFE sensor, EGR valve, and all associated hoses for damage, blockage, or improper connections.

2. Test the DPFE sensor signal and reference voltages using a multimeter. At idle, signal voltage should be 0.6-1.1 V. At 2000 RPM, it should be 2.2-2.8 V.

3. Perform an EGR flow test. Commanded flow at idle should be 0-10%. At 2000 RPM, it should be 30-40%.

4. If flow is insufficient, check for vacuum leaks, clean the EGR passages, and inspect the EGR valve.

5. If all other components check out, replace the DPFE sensor.

Solutions and Costs

In most cases, replacing the DPFE sensor will resolve a P1401 code. Ford released an upgraded DPFE sensor (part #4U7Z-9J460-AA) to address this common issue.

Replacement costs:

• DPFE Sensor: $30-100 USD / €25-85 EUR
• EGR Valve: $70-400 USD / €60-340 EUR
• Labor: 1-2 hours ($100-200 USD / €85-170 EUR)

Prevention

Regularly inspect and replace cracked or leaking vacuum hoses. If the EGR valve becomes sticky, clean the valve and passages. Use quality replacement parts if any components need to be replaced.

Related Issues

Other codes that may appear alongside P1401 include:

• P0401 – Insufficient EGR Flow
• P0402 – Excessive EGR Flow
• P1400 – DPFE Circuit Malfunction
• P1405 – DPFE Sensor Upstream Hose Off or Plugged

Frequently Asked Questions About P1401

What does the P1401 code mean?

P1401 is a diagnostic trouble code that indicates a problem with the Differential Pressure Feedback EGR (DPFE) sensor circuit. The code means the powertrain control module (PCM) has detected that the DPFE sensor signal voltage is above the expected range.

How urgent is a P1401 code?

If you get a P1401 code, stop driving immediately and have your vehicle repaired. Driving with a malfunctioning EGR system can lead to poor engine performance, increased emissions, and potential engine damage.

What vehicles are most likely to get a P1401 code?

While the P1401 code is most commonly associated with Ford vehicles from the late 1990s through the 2000s, it can apply to any vehicle equipped with a DPFE-type EGR system. However, the exact troubleshooting steps and part numbers may vary between makes and models.

What are the symptoms of a P1401 code?

Common symptoms include:

• Check engine light is on
• Rough idle
• Lack of power
• Failing emissions test
• Fuel odor from exhaust
• Pinging or knocking under load

What are the common causes of a P1401 code?

Potential causes include:

• Faulty DPFE sensor (most common)
• Damaged or blocked vacuum hoses to the DPFE sensor
• Stuck open EGR valve
• Plugged EGR passages or tube
• Leaks in the intake manifold
• Electrical short or open in the DPFE circuit
• Failed PCM (rare)

How do you diagnose a P1401 code?

1. Visually inspect the DPFE sensor, EGR valve, and all associated hoses for damage, blockage, or improper connections.

2. Test the DPFE sensor signal and reference voltages using a multimeter. At idle, signal voltage should be 0.6-1.1 V. At 2000 RPM, it should be 2.2-2.8 V.

3. Perform an EGR flow test. Commanded flow at idle should be 0-10%. At 2000 RPM, it should be 30-40%.

4. If flow is insufficient, check for vacuum leaks, clean the EGR passages, and inspect the EGR valve.

5. If all other components check out, replace the DPFE sensor.

What is the most common fix for a P1401 code?

In most cases, replacing the DPFE sensor will resolve a P1401 code. Ford released an upgraded DPFE sensor (part #4U7Z-9J460-AA) to address this common issue.

How much does it cost to fix a P1401 code?

Typical repair costs:

• DPFE Sensor: $30-100
• EGR Valve: $70-400
• Labor: 1-2 hours ($100-200)

Total cost is usually in the $130-500 range depending on what parts are required.

Can I drive with a P1401 code?

No, it's not recommended to drive with an active P1401 code. Doing so risks poor performance, increased emissions, and possible engine damage. Get the problem diagnosed and repaired as soon as possible.

Can a P1401 code cause a rough idle?

Yes, a malfunctioning EGR system from a P1401 code can allow too much or too little exhaust gas to enter the intake, disrupting proper combustion and causing a rough idle.

Will a P1401 code cause a failed emissions test?

Yes, an improperly functioning EGR system from a P1401 code will likely cause a failed emissions test due to increased NOx emissions. The vehicle will need to be repaired before it can pass.

Can a blown head gasket cause a P1401 code?

No, a blown head gasket would not directly cause a P1401 code. However, a major vacuum leak from a blown gasket could potentially trigger EGR system related codes like P1401 in some cases.

Can a clogged catalytic converter cause a P1401 code?

No, a clogged catalytic converter would not directly cause a P1401 code, as the code is specific to the EGR system. However, other codes related to catalytic converter efficiency may appear along with P1401.

Can a bad O2 sensor cause a P1401 code?

No, a bad O2 sensor would not directly cause a P1401 code. However, an O2 sensor fault could cause the PCM to incorrectly adjust the air-fuel mixture, indirectly affecting EGR operation over time.

Can a vacuum leak cause a P1401 code?

Yes, a major vacuum leak could potentially trigger a P1401 code, as it would affect the EGR system's ability to properly meter exhaust gases. Inspect and replace any cracked or leaking vacuum lines.

Can low coolant cause a P1401 code?

No, low coolant would not directly cause a P1401 code, as the code is specific to the EGR system. However, low coolant can cause overheating and head gasket issues that could potentially trigger EGR related codes in some cases.

Can a bad thermostat cause a P1401 code?

No, a bad thermostat would not directly cause a P1401 code. However, if the engine is not reaching proper operating temperature due to a stuck open thermostat, it could prevent the EGR system from functioning normally.

Can a bad mass airflow sensor cause a P1401 code?

No, a bad mass airflow sensor would not directly cause a P1401 code. However, an incorrect air flow reading could cause the PCM to miscalculate the proper EGR flow rate, potentially triggering EGR related codes over time.

Can a bad DPFE sensor cause transmission problems?

No, a bad DPFE sensor would not directly cause transmission problems. The DPFE sensor is only responsible for monitoring EGR flow and would not affect transmission operation. However, the root cause of a P1401 code like a major vacuum leak could potentially affect transmission performance in some cases.

How do I clear a P1401 code?

After repairing the root cause of the P1401 code, the code can be cleared by using an OBD-II scanner to reset the PCM. The code should then stay off if the repair was successful. If the code immediately returns, further diagnosis is needed.