Understanding the Ford P1473 Diagnostic Trouble Code
The OBD2 diagnostic trouble code (DTC) P1473 is a manufacturer-specific code primarily associated with Ford, Lincoln, and Mercury vehicles. Its official definition is “EVAP Leak Monitor Pinch Hose Circuit Malfunction.” This code is directly related to the vehicle’s Evaporative Emission Control (EVAP) system, which is designed to prevent fuel vapors from escaping into the atmosphere. Unlike generic EVAP codes, P1473 points to a specific component within Ford’s enhanced leak detection strategy: the Leak Detection Pump (LDP) system’s pinch hose solenoid or its control circuit.
What is the EVAP Leak Monitor Pinch Hose Circuit?
On many Ford models, the primary tool for finding small EVAP leaks is the Leak Detection Pump (LDP). The LDP creates a vacuum in the fuel tank and EVAP system. The “pinch hose” refers to a specific solenoid-controlled valve within this assembly. During a leak test, the Powertrain Control Module (PCM) commands this solenoid to pinch or close a hose, isolating sections of the system to perform a precise pressure or vacuum decay test. A P1473 code indicates that the PCM has detected an electrical fault in the circuit controlling this pinch hose solenoid—this could be an open circuit, short to ground, short to power, or a faulty solenoid itself.
Symptoms and Common Causes of P1473
While a P1473 code may not always cause immediate drivability issues, it will illuminate the Check Engine Light (MIL) and prevent the vehicle from passing an emissions test. The EVAP system is sealed, so any malfunction can have subtle effects.
Primary Symptoms of Code P1473
- Illuminated Check Engine Light (MIL): This is the most common and often the only noticeable symptom.
- Failed Emissions Inspection: The vehicle will fail due to the active EVAP system fault and incomplete monitor readiness.
- Possible Fuel Odor: In some cases, a related fault might prevent proper vapor purging, leading to a faint gasoline smell.
- Other EVAP Codes: P1473 may be stored alongside other codes like P0442, P0455, or P0456 if the circuit fault prevents a proper leak test.
Most Frequent Causes of P1473
- Faulty Leak Detection Pump (LDP) Assembly: The internal pinch hose solenoid is integrated into the LDP. A failed solenoid is the most common culprit.
- Damaged Wiring or Connectors: Corrosion, chafing, or rodent damage to the wiring harness connecting the LDP to the PCM.
- Poor Electrical Connections: Loose, corroded, or oxidized pins at the LDP connector or PCM.
- Blown Fuse: A fuse protecting the EVAP system or PCM power circuit may be blown.
- Rare PCM Failure: While uncommon, a faulty PCM that cannot properly control the solenoid circuit can set this code.
Step-by-Step Diagnosis for P1473
Diagnosing P1473 requires a systematic approach, starting with the simplest checks and moving toward component testing. You will need a quality OBD2 scanner and a digital multimeter (DMM).
Step 1: Preliminary Inspection and Code Verification
Begin with a thorough visual inspection. Locate the Leak Detection Pump (typically near the fuel tank or rear wheel well). Check for:
- Obvious physical damage to the LDP, hoses, or wiring.
- Corroded or disconnected electrical connectors.
- Damaged or pinched vacuum hoses connected to the LDP.
Clear the code with your scanner and perform a drive cycle. If P1473 returns immediately (without a drive cycle), it points to a hard electrical fault. If it returns after a drive cycle, the circuit is functional intermittently or under specific test conditions.
Step 2: Electrical Circuit Testing
Consult a vehicle-specific wiring diagram. The LDP connector typically has 3-4 wires: power, ground, and a control signal from the PCM.
- Check Power and Ground: With the ignition ON, use your DMM to verify battery voltage at the power pin. Check for a clean ground connection.
- Test the Solenoid Coil Resistance: Disconnect the LDP and measure resistance across the solenoid pins. Compare to manufacturer specifications (often between 10-30 ohms). An open (infinite ohms) or short (near 0 ohms) reading confirms a bad solenoid.
- Check for PCM Control Signal: Using a scan tool that can activate components, command the pinch hose solenoid ON and OFF. You should hear/feel a distinct click from the LDP. No click suggests a faulty solenoid or wiring issue.
Step 3: Pinpoint Testing and Component Replacement
If the solenoid tests bad or the circuit has a fault, perform a voltage drop test on the control wire from the PCM connector to the LDP connector to check for high resistance. If the wiring and power/ground are confirmed good, but the solenoid fails the resistance or activation test, the Leak Detection Pump assembly must be replaced. It is usually serviced as a complete unit.
Repair Solutions and Important Considerations
Once the root cause is identified, the repair is typically straightforward but requires attention to detail to ensure a lasting fix.
Replacing the Leak Detection Pump (LDP)
Replacement is the most common fix. Use OEM or high-quality aftermarket parts.
- Disconnect the negative battery cable as a safety precaution.
- Disconnect the electrical connector and vacuum hoses, noting their positions.
- Unbolt the LDP from its mounting bracket.
- Install the new unit, reconnect all hoses and the electrical connector securely.
- Reconnect the battery, clear all codes, and perform a complete drive cycle to run the EVAP monitor.
Clearing the Code and Completing the Drive Cycle
After repair, clear the DTCs with your scanner. The Check Engine Light will turn off. However, for the vehicle to be emissions-ready, the EVAP monitor must run and complete. This requires a specific drive cycle, often involving a mix of city and highway driving with a cool-down period. Use your scanner to check “Monitor Readiness Status” to confirm the EVAP monitor has passed.
Vehicle-Specific Notes for Ford Models
The P1473 code is prevalent on many Ford platforms from the late 1990s through the 2000s.
- Ford F-150, Expedition: The LDP is often located above the spare tire or near the fuel tank.
- Ford Explorer, Mercury Mountaineer: Common on 2002-2005 models; check for corroded connectors.
- Ford Focus: The LDP may be found in the rear quarter panel area.
Always reference a service manual for your specific model year for exact location and testing values.