P1402 Code on a 2006 Nissan Altima Sedan: Complete Diagnostic Guide
The “Check Engine” light illuminating on your 2006 Nissan Altima’s dashboard is always a cause for concern. When the fault code retrieved using an OBD2 scanner is P1402 2006 Nissan Altima Sedan, it specifically points to a problem within the Exhaust Gas Recirculation (EGR) system. Unlike other more general codes, P1402 is very specific and relates to the EGR differential pressure sensor, also known as the DPFE sensor. This detailed guide explains the causes, symptoms, and solutions to effectively resolve this issue and restore your vehicle’s optimal performance.
What Does the P1402 Code Mean on a 2006 Altima?
The P1402 error code is a generic code related to the EGR system. More specifically, it indicates that the Engine Control Module (ECM) has detected a malfunction in the exhaust gas recirculation pressure sensor circuit. On the 2006 Nissan Altima, this sensor is crucial. It measures the pressure difference between the two sides of the metal orifice that the EGR gases flow through. This data allows the ECM to accurately determine the flow rate of the recirculated gases and control the EGR valve accordingly to reduce NOx emissions.
Symptoms Associated with the P1402 Fault
When the P1402 code is stored in the ECM’s memory, you may observe one or more of the following symptoms on your 2006 Nissan Altima Sedan:
- The Check Engine light is permanently illuminated.
- Hesitation and misfires, especially during acceleration.
- Noticeable loss of power and poor engine performance.
- Increased fuel consumption.
- At idle, the engine may be rough or erratic.
- In rare cases, excessive pollutant emissions potentially leading to inspection failure.
Main Causes of the P1402 Code on a Nissan Altima
Several factors can be the origin of the P1402 code. It is essential to investigate them in order for an effective diagnosis.
- A faulty DPFE sensor: This is the most common cause. The sensor itself, located on the intake manifold, can fail and send erroneous signals to the ECM.
- Clogged or disconnected DPFE sensor hoses: The sensor is connected to the EGR system by two small rubber hoses. If they are clogged with carbon deposits, cracked, or simply disconnected, the sensor can no longer take correct readings.
- An electrical circuit problem: This could be an oxidized, loose, or corroded connector on the sensor, or a cut, chafed, or shorted wire between the sensor and the ECM.
- A faulty EGR valve: Although the code directly concerns the sensor, a stuck or clogged EGR valve can distort the measurements and trigger the fault.
Diagnostic Procedure and Solutions
Before replacing expensive parts, follow these steps to identify the root of the problem.
1. Visual Inspection
Start by locating the DPFE sensor on your engine (refer to the repair manual). Carefully inspect the two small rubber hoses connected to it. Check that they are securely fastened, without cracks, and not clogged. Inspect the electrical connector to ensure it is clean and fully seated.
2. Cleaning the Passages and EGR Valve
Disconnect the hoses from the DPFE sensor and blow compressed air through them to dislodge any potential deposits. It is also wise to remove and thoroughly clean the EGR valve and its orifice with a specific cleaner to remove carbon buildup.
3. Testing the DPFE Sensor
Using a multimeter, you can test the sensor. The exact procedure varies, but it generally involves checking the reference voltage (often 5V) and the return signal at idle and during slight acceleration. A value that does not change indicates a dead sensor.
4. Replacing Faulty Parts
If the previous steps have not resolved the issue, replacing the DPFE sensor is the most likely solution. It is a relatively affordable and simple part to change. After replacement, clear the fault code with your scanner and take a test drive to confirm the repair.
Conclusion
The P1402 2006 Nissan Altima Sedan code is not a foregone conclusion. Although annoying, it is often resolved by meticulously cleaning the passages or replacing a faulty DPFE sensor. By performing a methodical diagnosis, you can avoid unnecessary repairs and restore your vehicle to its optimal operation, ensuring low emissions and a smooth drive.