What is Volkswagen OBD2 Code P1470?
OBD2 diagnostic trouble code P1470 is a manufacturer-specific code for Volkswagen, Audi, and other Volkswagen Group vehicles. It is defined as “Leak Detection Pump Circuit Malfunction”. This code is directly related to the vehicle’s Evaporative Emission Control (EVAP) system, a critical component for reducing hydrocarbon emissions and maintaining fuel efficiency. The Leak Detection Pump (LDP) is an electrically-operated pump, often combined with a solenoid valve, that pressurizes the fuel vapor system to check for leaks. When the vehicle’s Engine Control Module (ECM) detects an electrical fault within the LDP’s control circuit—such as an open, short to ground, or short to power—it stores code P1470 and illuminates the check engine light.
Symptoms and Causes of a P1470 Fault Code
A stored P1470 code will trigger the check engine light (MIL) on your dashboard. While the vehicle may often drive normally, the underlying electrical fault prevents the EVAP system from performing its required self-tests, which can lead to failed emissions inspections.
Common Symptoms of Code P1470
- Illuminated Check Engine Light (MIL): The primary and most common symptom.
- Failed Emissions Test: The EVAP monitor will be incomplete or failed.
- Possible Fuel Odor: While less common with a circuit fault, a compromised EVAP system can sometimes lead to a smell of gasoline.
- No Other Drivability Issues: The engine typically runs, starts, and idles normally as this is not a fuel delivery or ignition fault.
Primary Causes of P1470
- Failed Leak Detection Pump (LDP): The internal motor or solenoid windings have burned out or shorted.
- Damaged Wiring or Connectors: Corroded, broken, or chafed wires in the harness to the LDP, or a loose/dirty electrical connector.
- Blown Fuse: A dedicated fuse for the LDP circuit may be blown.
- Faulty ECM (Rare): In rare instances, the engine control module itself may have an internal driver circuit failure.
- Physical Damage: The LDP, often located near the fuel tank or in the wheel well, can be damaged by road debris or corrosion.
Step-by-Step Diagnostic Procedure for P1470
Proper diagnosis is key to an effective repair. Jumping straight to replacing the Leak Detection Pump can be costly and may not solve the issue if the problem lies in the wiring. Follow this systematic approach.
Step 1: Preliminary Checks and Code Verification
Begin by using a professional-grade OBD2 scanner to confirm the code is present and active. Clear the code and perform a test drive to see if it returns immediately (indicating a hard fault) or after a few drive cycles. Visually inspect the Leak Detection Pump (common locations: under the vehicle near the fuel tank, behind the rear wheel liner, or in the engine bay) and its wiring harness for obvious damage, corrosion, or disconnection.
Step 2: Electrical Circuit Testing
This requires a digital multimeter (DMM). Locate the wiring diagram for your specific VW/Audi model. The LDP typically has a 2-pin or 4-pin connector.
- Check Power Supply: With the ignition ON, back-probe the connector to check for battery voltage (usually 12V) at the designated power wire.
- Check Ground Circuit: Test the ground wire for continuity to a known good chassis ground.
- Check Control Signal: Using a scan tool with bidirectional controls or an oscilloscope, command the LDP ON and OFF. You should see the voltage at the control pin from the ECM change state.
Step 3: Component Testing
If power and ground are present, test the Leak Detection Pump itself. Disconnect it and measure its resistance across the motor/solenoid terminals. Consult a repair database for the specific resistance specification (typically between 10-30 ohms). A reading of infinite resistance (open) or zero resistance (short) confirms a faulty pump.
Step 4: Checking for Related Codes
Always check for other codes. Codes like P0441, P0442, or P0455 (general EVAP system faults) may appear alongside P1470, pointing to a larger EVAP system issue possibly caused by the inoperative LDP.
Repair Solutions and Replacement Guide
Once the faulty component is identified, proceed with the repair. For Volkswagen and Audi vehicles, using OEM or high-quality aftermarket parts is recommended for reliability.
Replacing the Leak Detection Pump
Replacement procedures vary by model. Common steps include:
- Safely raising and supporting the vehicle.
- Removing the rear wheel and/or wheel liner for access (common on Golf, Jetta, Passat).
- Disconnecting the electrical connector and vacuum/purge lines.
- Unbolting the pump bracket or the pump itself from its mount.
- Installing the new pump, reconnecting all lines and the electrical connector.
- Clearing fault codes and performing an EVAP system test cycle with a scan tool.
Repairing Wiring Harness Issues
If the wiring is damaged, repair it using solder and heat-shrink tubing or a quality crimp connector. Ensure the repair is sealed from moisture. Always address the root cause of the wire damage (e.g., securing a loose harness away from moving parts).
Preventative Maintenance and Final Notes
While circuit failures are often unpredictable, keeping the undercarriage clean and avoiding impacts can protect the LDP. After any repair for P1470, it is crucial to clear the codes and perform a complete EVAP system monitor drive cycle to ensure the system passes its self-test. This is necessary to turn off the check engine light and prepare the vehicle for an emissions test. Diagnosing P1470 requires a methodical approach, but with basic electrical knowledge and the right tools, it is a manageable repair for the serious DIYer or a straightforward task for a professional technician.