What Is Code P1402?
Code P1402 is a manufacturer-specific diagnostic trouble code used by Nissan to indicate a problem with the EGR (Exhaust Gas Recirculation) system function. Unlike generic OBD-II codes (P0xxx), this code is unique to Nissan vehicles and signals that the engine control module (ECM) has detected a malfunction in how the EGR system is operating. The EGR system is critical for reducing emissions and maintaining proper engine performance, so this code should be addressed promptly.
What Does P1402 Mean?
The EGR system works by recirculating a portion of exhaust gases back into the engine’s intake manifold. This process reduces combustion temperatures and lowers harmful nitrogen oxide (NOx) emissions. When the ECM detects that the EGR system isn’t functioning as expected—whether the valve isn’t opening, closing, or responding correctly—it sets code P1402.
This code can indicate several different problems within the EGR system, ranging from a stuck valve to electrical issues, sensor failures, or clogged passages. The exact cause depends on your vehicle’s model year and engine type, but the underlying issue is always related to EGR system performance.
Common Symptoms
- Check Engine Light: The most obvious sign—the MIL (malfunction indicator lamp) illuminates on your dashboard
- Rough Idle: Engine runs unevenly or shakes at stoplights
- Reduced Fuel Economy: You notice fewer miles per gallon than usual
- Engine Knocking/Pinging: Metallic noise under acceleration, especially with low-octane fuel
- Hesitation or Stumbling: Engine hesitates when accelerating from a stop
- Increased Emissions: Visible exhaust smoke or failed emissions test
- Loss of Power: Noticeable reduction in engine performance
- No Symptoms: Sometimes the code sets with no noticeable drivability issues
Possible Causes (Ranked by Frequency)
1. Stuck or Clogged EGR Valve
The most common cause of P1402 is a stuck EGR valve, usually due to carbon buildup. Over time, exhaust gases deposit carbon inside the valve, preventing it from opening or closing properly. This is especially common in higher-mileage vehicles or those with irregular maintenance.
2. EGR Valve Failure
The EGR valve itself may be faulty or worn out. Internal seals can degrade, or the solenoid that controls the valve can fail, preventing proper operation.
3. Clogged EGR Passages
Carbon buildup in the EGR passages (tubes and ports) can restrict exhaust gas flow, preventing the system from functioning correctly. This often occurs alongside a stuck valve.
4. EGR Sensor Malfunction
Nissan vehicles use EGR position sensors or feedback sensors to monitor valve operation. A faulty sensor can cause the ECM to think the system isn’t working, even if it is.
5. Wiring or Connector Issues
Corroded, loose, or damaged wiring and connectors in the EGR circuit can prevent proper communication between the valve and the ECM.
6. EGR Cooler Problems
Some Nissan models use an EGR cooler to reduce exhaust gas temperatures. A leaking or clogged cooler can affect system function.
7. ECM or Software Issues
Rarely, the ECM itself may be faulty or require a software update to properly control the EGR system.
Diagnostic Steps
Step 1: Confirm the Code with a Scanner
Use an OBD-II scanner to read the code and check for any additional codes. P1402 may appear alongside other EGR-related codes (like P0400 or P0401) that provide additional diagnostic clues.
Step 2: Visual Inspection
Inspect the EGR valve, hoses, and connectors for:
- Loose or corroded connectors
- Cracked or disconnected vacuum hoses
- Visible carbon buildup around the valve
- Leaking coolant (if an EGR cooler is present)
Step 3: Check EGR Valve Operation
With the engine running, listen for a clicking sound from the EGR solenoid when the engine is first started. If you hear no clicking, the solenoid may be faulty. You can also apply vacuum directly to the valve (if equipped) to test manual operation.
Step 4: Test EGR Sensor Output
Using a multimeter or scanner, check the EGR position sensor voltage. Compare readings to your vehicle’s service manual specifications. A sensor reading outside the normal range indicates a faulty sensor.
Step 5: Inspect Wiring and Connectors
Check the EGR valve connector and wiring harness for corrosion, loose pins, or damage. Clean corroded connectors with electrical contact cleaner and ensure all connections are tight.
Step 6: Clean or Replace the EGR Valve
If the valve appears clogged with carbon, it can often be removed and cleaned with carburetor cleaner or a specialized EGR cleaning solution. If cleaning doesn’t restore function, replacement is necessary.
Step 7: Check for Vacuum Leaks
Inspect all vacuum hoses connected to the EGR system for cracks or disconnection. Use a smoke test if necessary to identify hard-to-spot leaks.
Step 8: Clear the Code and Test Drive
After repairs, clear the code with your scanner and take a test drive under various conditions (city driving, highway, acceleration). If the code doesn’t return after 50–100 miles, the repair was successful.
Repair Cost Estimates
EGR Valve Cleaning: $150–$300 (DIY-friendly if you’re mechanically inclined; professional shop labor typically $1–2 hours)
EGR Valve Replacement: $250–$600 (parts: $100–$300; labor: $150–$300 depending on accessibility)
EGR Cooler Replacement: $400–$900 (if the cooler is faulty; more labor-intensive)
EGR Sensor Replacement: $100–$250 (relatively inexpensive part and labor)
Wiring/Connector Repair: $50–$200 (minimal cost if only cleaning or tightening is needed)
Full EGR System Diagnosis: $100–$150 (diagnostic fee that may be waived if you proceed with repairs)
Note: Costs vary significantly by Nissan model, engine type, and your location. Always get a quote from your mechanic before authorizing work.
Can I Still Drive?
Severity: Moderate
In most cases, you can continue driving with code P1402 set, though it’s not ideal. The vehicle will likely run rough, experience reduced fuel economy, and may fail an emissions test. However, the engine won’t be damaged by driving with this code present.
Safety Considerations:
- If the vehicle is experiencing severe hesitation or loss of power, avoid highway driving until the issue is resolved
- The check engine light indicates an emissions system problem, which may prevent vehicle registration renewal in some states
- Continued driving with a stuck-open EGR valve can lead to engine overheating in some cases
- If you’re experiencing engine knock, avoid hard acceleration and use premium fuel if possible
Recommendation: Schedule a repair within a week or two. This isn’t an emergency, but addressing it promptly will improve performance, fuel economy, and emissions compliance.
Frequently Asked Questions
Q: Can I drive with P1402 code?
A: Yes, you can typically drive with P1402 set, though the engine may run rough and fuel economy will suffer. The code indicates an emissions system malfunction rather than a critical engine problem. However, you should schedule a repair soon to restore proper performance and avoid failing an emissions test.
Q: Is P1402 the same as P0400 or P0401?
A: No. P1402 is Nissan-specific, while P0400 (EGR System Malfunction) and P0401 (EGR Flow Insufficient) are generic codes used across all manufacturers. P1402 indicates a Nissan-specific EGR system issue. If you see multiple codes together, it helps pinpoint the exact problem.
Q: Can I clean the EGR valve myself?
A: Yes, if you have basic mechanical skills. The EGR valve can usually be removed with basic hand tools, then soaked in carburetor cleaner to remove carbon buildup. However, if the valve is damaged or the solenoid is faulty, replacement is necessary. Always consult your vehicle’s service manual for specific procedures and torque specifications.
Q: How much does it cost to fix P1402?
A: Costs range from $150–$900 depending on the cause. A simple cleaning might cost $150–$300, while a full valve replacement typically runs $250–$600. EGR cooler replacement (if needed) can exceed $900. Get a diagnostic from your mechanic to determine the exact cause and cost.
Q: Will P1402 go away on its own?
A: No. P1402 will persist until the underlying EGR system problem is fixed. The code may clear temporarily if you disconnect the battery, but it will return once the vehicle detects the fault again. Proper repair is required for permanent resolution.
Q: What’s the most common fix for P1402?
A: Cleaning or replacing the EGR valve is the most common solution, accounting for the majority of P1402 cases. Carbon buildup is the primary culprit, and a thorough cleaning often restores function without requiring a full replacement.