Fix P0445: Mechanic’s solutions that WORKED

The P0445 code indicates a problem with the Evaporative Emission Control System’s purge control valve circuit, specifically a short circuit. This valve is responsible for controlling the flow of fuel vapor from the charcoal canister to the engine intake manifold. When a short circuit is detected in the circuit, it triggers this fault code.

P0445 quick overview

Meaning	P0445: Evaporative Emission Control System Purge Control Valve Circuit Shorted
Is it serious?	This code is generally not serious and should not lead to immediate vehicle breakdown. However, it may affect emissions control and fuel efficiency.
Possible causes	– Faulty purge control valve – Short circuit or wiring issue in the purge control valve circuit – Corroded or loose connectors in the circuit – Environmental factors affecting the valve’s operation
How to diagnose?	Locate Purge Control Valve: Find the purge control valve’s location in your vehicle, typically near the engine or the charcoal canister. Inspect Wiring and Connectors: Examine the wiring and connectors connected to the purge control valve for damage, loose connections, or corrosion. Test Purge Control Valve: Test the purge control valve’s functionality using a diagnostic tool or by applying voltage to it and checking for proper operation. Clear Diagnostic Codes: After any necessary repairs or replacements, use a diagnostic tool to clear the fault code and monitor if it returns.

How to fix P0445 – learn from mechanics

I looked into P0445 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Ford

Vehicle Information: 1998 Ford Expedition Eddie Bauer 5.4L

Issue + Repair History:

• MIL lamp on with code PO445.
• Initially unable to find leaks using a smoke machine.
• Replaced purge and vent solenoid but the light returned after 200 miles.
• Suspected issues with the fuel system or ECM.

Computer Codes & Descriptions:

• PO445 – Large fuel vapor leak

Suggestions to Fix Issue:

• Verify the PCM is receiving signals from the purge solenoid.
• Check the gas cap for proper sealing and condition.
• Consider potential issues with the FTP (Fuel Tank Pressure) sensor.
• Inspect the fuel filler pipe for cracks or damage.
• Evaluate vacuum hoses for proper routing and condition.
• Check the flow sensor for faults.

Final Fix:

• Identified and addressed a crack on the metal part of the neck where the gas cap goes using black silicon.
• Applied silicon grease to the gas cap seal and neck.
• After these adjustments, the code did not set back.

Case #2: Land Rover

Vehicle Information: 2004 Land Rover Discovery SE 4.6L

Issue + Repair History:

• MIL lamp on after vehicle ran out of gas a few months ago.
• No previous issues noted until this incident.
• Evap purge solenoid cycled during leak test with no leak found.
• Replaced fuel filler cap with an OEM part.
• Fault code cleared twice but resets.

Computer Codes & Descriptions:

• PO445 – Very small EVAP leak

Other Test Results:

• Visual inspection of all lines, hoses, valves, tank etc., all okay.
• Customer stated the car was never in an accident.
• Evap pressure test and smoke test showed no leak detected.

Suggestions to Fix Issue:

• Replace the purge valve as it is commonly associated with small EVAP leaks.
• Consider removing the fuel tank to inspect for leaks not detectable externally.
• Fill the tank very full and use a smoke machine to detect any possible leaks.
• Spray with soapy water to look for bubbles indicating a leak.

Final Fix:

• Advised the customer to replace the purge valve as the initial step in resolving the issue.
• Car also has a head gasket leak; customer is considering getting rid of the vehicle.

Case #3: Chevrolet

Vehicle Information: 2005 Chevrolet Suburban 1500 LT 5.3L

Issue + Repair History:

• Slow gas tank fill and codes PO446 & PO445.
• Canister was full of gas and disintegrated, sending pieces into the system.
• Replaced canister, vent solenoid valve, and purge valve.
• Despite repairs, still experiencing slow fill and kick-back during gas filling.

Computer Codes & Descriptions:

• PO446 – Evap
• PO445 – Evap

Suggestions to Fix Issue:

• Check the rollover valve at the end of the fill pipe.
• Inspect the vent line from the fill neck to the tank.
• Remove the filler hose and check the rollover valve.
• Examine the vent tube on top of the tank for pinching, especially on the frame.
• Investigate the fuel limiter vent valve, which may be part of the fuel pump.
• Look down the fill pipe for any foreign objects.
• Ensure the tank’s vent line is not pinched under the cross member.

Final Fix:

• Discovered that the vent line was pinched. After resolving this issue, the problem was fixed.

Case #4: Kia

Vehicle Information: 2003 Kia Optima SE 2.7L

Issue + Repair History:

• Car towed in; initially, it ran poorly and stalled.
• Customer attempted to replace crank sensor but broke it in the block.
• After replacing the crank sensor, the car wouldn’t start.
• Codes P0230 and P0445 were found.
• Discovered no injector signal and no spark.

Computer Codes & Descriptions:

• P0230 – Fuel pump primary circuit fault
• P0445 – Evap purge circuit short

Suggestions to Fix Issue:

• Check the fuel pump relay in the engine fuse box.
• Inspect the main relays in the center stack, a common issue in these models.
• Access wiring diagrams for further testing, particularly for the main relay.
• Clean all body grounds and test with an ohm meter.
• Consider the possibility of the car having jumped time.

Final Fix:

• The issue was resolved by replacing the main relay.
• Initial confusion arose due to a mix-up between the fuel pump relay and the main relay in the wiring diagrams.

Case #5: Volkswagen

Vehicle Information: 2002 Volkswagen Jetta GLS 2.0L

Issue + Repair History:

• Multiple codes stored: P0261, P0267, P0270, P0264 (all injector current low or short to ground), P0445, P0037.
• Battery cables were previously replaced due to corrosion.
• Customer reported hard starting when the fuel tank is in lower levels.

Suggestions to Fix Issue:

• Start by replacing the fuel pump relay, which can cause multiple shorting codes.
• Check for loose or corroded grounding posts under the wiper cover.
• Inspect the ECM for water damage to the terminals.
• Consider cutting the ground wire at the coil about 2 inches from the connector and run it to a good ground source.
• Note that the fuel pump relay in VW models supplies power to various components, and they don’t last long; it has been updated multiple times.

Final Fix:

• The issue was resolved by replacing the fuel pump relay. The relay is located up under the dash in the relay center.

Advice	Diagnostic Step Description
Check for Water Damage to ECM Terminals	Water damage to ECM terminals can cause electrical issues. Inspect for any signs of moisture or corrosion.
Clean or Replace Battery Cables	Corroded or damaged battery cables can lead to electrical problems. Clean or replace the cables as needed.
Verify Fuel Pump Relay Operation	Ensure the fuel pump relay is functioning correctly to avoid shorting codes. Test or replace if necessary.
Inspect Fuel Pump Circuit	Check the fuel pump circuit for any issues that could trigger shorting codes, such as damaged wiring or connectors.
Address Grounding Issues	Look for grounding problems, including loose or damaged ground wires, and resolve them to improve electrical connections.