Understanding OBD2 Code P14AA in Your Infiniti
The illumination of the check engine light in your Infiniti, accompanied by diagnostic trouble code (DTC) P14AA, signals a specific fault within the vehicle’s Evaporative Emission Control (EVAP) system. This code is manufacturer-specific, primarily used by Nissan and its luxury division, Infiniti. In technical terms, P14AA is defined as “EVAP Canister Pump Control Circuit.” This system is crucial for environmental compliance, preventing fuel vapors from escaping into the atmosphere by storing them in a charcoal canister and later purging them into the engine for combustion. A fault here can affect drivability, fuel efficiency, and will cause your vehicle to fail an emissions test.
What is the EVAP Canister Pump (Leak Detection Pump)?
Unlike generic EVAP codes, P14AA points directly to the component responsible for actively testing the system for leaks. Often called the Leak Detection Pump (LDP) or Canister Pump, this device is an electric pump controlled by the Engine Control Module (ECM). During specific drive cycles, the ECM activates the pump to pressurize the EVAP system. By monitoring the pump’s operation and the resulting pressure, the ECM can determine if a leak of a specific size is present. Code P14AA indicates a problem with the electrical control circuit of this pump—this could be an open, short, high resistance, or a failure of the pump motor itself.
Symptoms and Common Causes of P14AA
While sometimes the P14AA code may set without any noticeable drivability issues, it often presents with identifiable symptoms. Recognizing these can help correlate the code with a tangible vehicle behavior.
Primary Symptoms of Code P14AA
- Illuminated Check Engine Light (MIL): The most common and often the only initial symptom.
- Failed Emissions Inspection: The vehicle will not pass a state or local smog check due to an active EVAP system fault.
- Possible Fuel Odor: In some cases, a minor leak or venting issue may cause a faint smell of gasoline, especially near the fuel tank or rear of the vehicle.
- Other EVAP Codes: P14AA may appear alongside related codes like P0442, P0455, or P0456 (small/ large evaporative leaks) if the pump failure prevents proper leak testing.
Most Frequent Causes of P14AA in Infiniti Models
- Failed EVAP Canister Pump / Leak Detection Pump: The internal electric motor or mechanism of the pump itself has worn out or failed. This is a very common culprit.
- Damaged Wiring or Connectors: Corrosion, rodent damage, or physical breaks in the wiring harness to the pump can disrupt the control circuit.
- Poor Electrical Connections: A loose, corroded, or oxidized connector at the pump or the ECM can cause high resistance.
- Blown Fuse or Faulty Relay: The circuit supplying power to the EVAP pump may be interrupted by a blown fuse or a failed relay (check the vehicle’s IPDM E/R or fuse box).
- Faulty Engine Control Module (ECM): Although rare, an internal failure within the ECM that prevents it from properly controlling the pump circuit can set this code.
- Blocked or Pinched EVAP Lines: A severely blocked vent line can cause the pump to overwork or fail, potentially triggering a circuit code.
Step-by-Step Diagnostic Procedure for P14AA
Proper diagnosis is key to avoiding unnecessary parts replacement. Follow this systematic approach. Warning: Always consult your Infiniti’s specific service manual for precise values, connector locations, and safety procedures.
Step 1: Preliminary Checks & Code Verification
Begin by using a professional-grade OBD2 scanner to confirm the code and check for any other pending codes. Clear the code and perform a test drive to see if it returns immediately (indicating a hard fault) or after several drive cycles (indicating an intermittent issue). Visually inspect the EVAP canister pump (typically located near the fuel tank or charcoal canister) and its wiring harness for obvious damage, corrosion, or disconnections.
Step 2: Electrical Circuit Testing
With the vehicle’s ignition OFF, disconnect the electrical connector from the EVAP canister pump. Using a digital multimeter (DMM):
- Check for power supply (reference wiring diagram for correct pin). With ignition ON, you should have system voltage (approx. 12V) at the designated power pin.
- Check for ground circuit integrity. Measure resistance between the ground pin and a known good chassis ground; it should be very low (less than 5 ohms).
- Check the control signal circuit from the ECM for continuity and shorts to ground or power.
If power and ground are correct, the fault likely lies with the pump itself or the ECM control signal.
Step 3: Component Testing – The EVAP Canister Pump
Test the pump’s internal motor. Using the DMM on the Ohm (Ω) setting, measure the resistance across the pump’s motor terminals (at the component side, not the harness). Consult service data for the exact specification, but typical resistance for a small DC motor ranges from 10 to 50 ohms. A reading of infinite resistance (open) or zero ohms (short) confirms a failed pump. You can also carefully apply 12V directly to the pump terminals (observing polarity) to see if it activates; a functional pump will hum or click briefly.
Repair Solutions and Professional Recommendations
Once the faulty component is identified, repairs can be undertaken. The complexity ranges from simple connector service to component replacement.
Common Repairs for P14AA
- Replacing the EVAP Canister Pump: This is the most common fix. The pump is usually mounted with bolts or clips and connected to the EVAP hose assembly. Ensure you use an OEM or high-quality aftermarket part.
- Repairing Wiring Harness: For damaged wires, solder and seal the repair with heat-shrink tubing. Never use twist-on connectors in automotive environments.
- Cleaning Electrical Connectors: Use electrical contact cleaner and a small brush to remove corrosion from both the pump and harness connectors.
- Replacing Fuses/Relays: Locate the relevant fuse (often in the under-hood Intelligent Power Distribution Module – IPDM) and relay, testing and replacing as necessary.
Post-Repair Procedure and Final Notes
After completing the repair, clear all DTCs with your scanner. To fully extinguish the check engine light and run the EVAP monitor (required for emissions readiness), you must perform a specific drive cycle. This typically involves a mix of city and highway driving under varying conditions. Use your scanner to monitor the “EVAP Monitor” status; it should change from “Incomplete” to “Ready” or “Complete.” If the code returns, re-evaluate your diagnosis, as there may be an intermittent fault or an issue with the ECM.
Addressing a P14AA code promptly is important for your vehicle’s emissions integrity and to prevent potential fuel vapor leaks. While a skilled DIYer with the right tools can diagnose this code, the location of the pump (often under the vehicle) and the need for precise electrical testing make this a job where professional assistance is often beneficial for Infiniti owners.