P1404 Code: EGR Closed Position Performance
The P1404 is a diagnostic trouble code (DTC) specific to General Motors vehicles that indicates the Engine Control Module (ECM) has detected the Exhaust Gas Recirculation (EGR) valve is stuck open.
In our workshop, we've seen the P1404 code pop up quite frequently, especially on European makes like Mercedes-Benz, BMW, and Volkswagen. Just last week, a customer brought in their 1997 Mercedes E300D with the check engine light on and going into limp mode. After some diagnostics, we traced it to a P1404 EGR code. We cleaned the EGR valve and passages, replaced the position sensor, but the code kept coming back. Turned out the wiring to the EGR valve was damaged, likely from the heat in that area. Once we repaired the wiring, the code was gone for good. It's a common problem area on these cars as they age. We've seen similar issues on the BMW M57 and VW TDI engines too. The key is thorough diagnosis to find the root cause, as the EGR valve itself isn't always the culprit.
Urgency and Severity
STOP DRIVING IMMEDIATELY. A stuck open EGR valve can lead to rough idling, stalling, increased fuel consumption, and potentially severe engine damage. The vehicle should be towed to a repair shop or dealership for diagnosis and repair.
Technical Details
The ECM monitors the EGR Valve Position Sensor, a potentiometer that provides feedback on the actual position of the EGR valve pintle. When the ECM commands the EGR valve closed, it expects the position sensor voltage to be below 0.29V. If the voltage remains above 0.29V, the ECM determines the valve is stuck open and sets a P1404 code.
On most other vehicle makes, a stuck open EGR valve would set the generic OBD-II code P0404 instead.
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Parts Involved
- EGR Valve: Allows a portion of the exhaust gases to recirculate back into the intake manifold to lower peak combustion temperatures and reduce NOx emissions
- EGR Valve Position Sensor: A potentiometer mounted on the EGR valve that provides a voltage signal to the ECM indicating the valve pintle position
- Engine Control Module (ECM): Controls the EGR system and monitors the position sensor for rationality
Common Causes
Potential causes for a P1404 code include:
- Faulty EGR valve (most common)
- Carbon buildup restricting EGR valve movement
- Faulty EGR valve position sensor
- Wiring issues in the EGR valve control or position sensor circuits
- Faulty ECM (rare)
Diagnosis Steps
- Verify poor idle quality and possible stalling condition
- With the engine idling, check EGR Valve Position Sensor voltage with a multimeter at the sensor connector. Normal voltage range is 0.14-1.07V.
- If voltage is over 0.29V, disconnect the EGR valve and see if idle quality returns to normal. If so, the EGR valve is likely stuck open.
- Check reference voltage, ground, and signal wiring between the EGR valve and ECM for opens, shorts, or high resistance.
Repair Options
- Replace a faulty EGR valve
- Clean carbon deposits from the EGR valve and passages
- Repair wiring issues in the EGR circuits
- Replace a faulty EGR Valve Position Sensor
- As a last resort, the ECM may require replacement if no other faults can be found
Prevention
- Use Top Tier fuel to minimize carbon buildup in the EGR system
- Address EGR-related DTCs promptly to prevent excess engine wear
- Maintain the engine in good overall condition
Repair Cost
Repair costs can vary depending on the root cause:
| Part | Cost (USD) | Cost (EUR) |
|---|---|---|
| EGR Valve | $120 – $500 | €100 – €420 |
| EGR Position Sensor | $80 – $200 | €67 – €170 |
| Labor (1 hour) | $80 – $150 | €67 – €125 |
Typical total repair cost ranges from $200 – $700 (€170 – €600).
Related Codes
Other codes that may appear along with P1404 include:
- P0401 – Insufficient EGR Flow
- P0406 – EGR Sensor Out of Range
Diagnosing and repairing a P1404 code promptly is critical to prevent driveability issues and engine damage. Consult a professional technician for assistance.
Frequently Asked Questions about P1404 Code
What does the P1404 code mean?
The P1404 is a diagnostic trouble code for "EGR Closed Position Performance". It indicates that the Engine Control Module (ECM) has detected that the Exhaust Gas Recirculation (EGR) valve is stuck open.
How serious is a P1404 code?
A P1404 code is very serious. Stop driving immediately and have your vehicle repaired. Driving with a stuck open EGR valve can lead to rough idling, stalling, increased fuel consumption, and potentially severe engine damage.
Is it safe to drive with a P1404 code?
No, it is not safe to drive with a P1404 code. The vehicle should be towed to a repair shop or dealership for diagnosis and repair to prevent further engine damage.
What are the symptoms of a P1404 code?
Symptoms of a P1404 code include:
- Check Engine Light is on
- Rough idle quality, possibly stalling
- Hesitation on acceleration
- Increased fuel consumption
What causes a P1404 code?
Potential causes for a P1404 code include:
- Faulty EGR valve (most common)
- Carbon buildup restricting EGR valve movement
- Faulty EGR valve position sensor
- Wiring issues in the EGR valve control or position sensor circuits
- Faulty ECM (rare)
How do you diagnose a P1404 code?
To diagnose a P1404 code:
- Verify poor idle quality and possible stalling condition
- Check EGR Valve Position Sensor voltage at the sensor connector with the engine idling. Normal range is 0.14-1.07V.
- If voltage is over 0.29V, disconnect the EGR valve and see if idle quality returns to normal. If so, the EGR valve is likely stuck open.
- Check reference voltage, ground, and signal wiring between the EGR valve and ECM for opens, shorts, or high resistance.
How do you fix a P1404 code?
To fix a P1404 code, one or more of the following repairs may be needed:
- Replace a faulty EGR valve
- Clean carbon deposits from the EGR valve and passages
- Repair wiring issues in the EGR circuits
- Replace a faulty EGR Valve Position Sensor
- Rarely, the ECM may require replacement if no other faults can be found
Can a P1404 code clear itself?
It's possible for a P1404 code to clear itself if the condition that caused it is intermittent. However, because a stuck open EGR valve can cause driveability issues and engine damage, it's best to have the code diagnosed and repaired promptly.
Is the P1404 code specific to certain makes?
The P1404 code is specific to General Motors (GM) vehicles. On most other makes, a stuck open EGR valve would set the generic P0404 code instead.
What is the EGR system and what does it do?
The Exhaust Gas Recirculation (EGR) system routes a portion of the exhaust gases back into the intake manifold. This lowers peak combustion temperatures to reduce the formation of nitrogen oxide (NOx) pollutants. The EGR valve controls the flow of exhaust gases based on engine conditions.
Can a stuck open EGR valve cause a misfire?
Yes, a stuck open EGR valve can cause a misfire. Excessive exhaust gas recirculation can dilute the air/fuel mixture and interfere with normal combustion, especially at idle.
What does the EGR Valve Position Sensor do?
The EGR Valve Position Sensor is a potentiometer mounted on the EGR valve that provides a voltage signal to the ECM indicating the valve pintle position. The ECM uses this feedback to detect EGR system faults.
How much does it cost to fix a P1404 code?
Repair costs for a P1404 code can vary depending on the root cause:
- EGR Valve: $120 – $500
- EGR Position Sensor: $80 – $200
- Labor (1 hour): $80 – $150
Typical total repair cost ranges from $200 – $700.
Can low engine coolant cause a P1404 code?
Low engine coolant will not directly cause a P1404 code, as the code is related to the EGR valve being stuck open. However, low coolant can cause the engine to run hotter than normal, which could lead to increased carbon buildup on the EGR valve over time.
Can a vacuum leak cause a P1404 code?
A vacuum leak would not directly set a P1404 code. However, a large vacuum leak could cause a lean air/fuel mixture and rough idle similar to the symptoms of a stuck open EGR valve. Proper diagnosis is important to determine the actual cause.
What are some other common EGR system fault codes?
Other common EGR system codes include:
- P0400 – Exhaust Gas Recirculation Flow Malfunction
- P0401 – Exhaust Gas Recirculation Flow Insufficient
- P0402 – Exhaust Gas Recirculation Flow Excessive
- P0403 – Exhaust Gas Recirculation Circuit Malfunction
- P0404 – Exhaust Gas Recirculation Circuit Range/Performance
- P0405 – Exhaust Gas Recirculation Sensor A Circuit Low
- P0406 – Exhaust Gas Recirculation Sensor A Circuit High
How often do EGR valves need to be replaced?
There is no specific mileage interval at which the EGR valve needs to be replaced. EGR valves can last the lifetime of the vehicle, but they are a common failure item. Factors like short trip driving, poor fuel quality, and infrequent maintenance can cause the valve to fail prematurely due to carbon buildup.
Can you clean an EGR valve?
In some cases, an EGR valve can be cleaned if the carbon buildup is not too severe. However, cleaning the valve does not guarantee the problem will be fixed, especially if the valve pintle or seat is damaged. Replacing the valve is often the most reliable repair.
What should I do if the P1404 code keeps coming back?
If a P1404 code persists after replacing the EGR valve, there may be an underlying wiring issue, faulty EGR position sensor, or carbon buildup in the EGR passages preventing the valve from fully closing. Further diagnosis is needed to pinpoint the root cause and prevent the problem from reoccurring.
How can I prevent EGR system problems?
To help prevent EGR system issues:
- Use high quality fuel to minimize carbon buildup
- Have any EGR-related codes diagnosed and repaired promptly
- Follow the manufacturer's recommended maintenance schedule
- Address other engine performance issues that can contribute to increased carbon buildup
If you suspect your vehicle has a stuck open EGR valve or is displaying a P1404 trouble code, have it diagnosed by a professional technician as soon as possible to prevent driveability issues and costly engine damage.