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P0443 is a circuit fault - the PCM can't properly control the purge valve electrically. Unlike P0441 (flow fault), P0443 is an electrical circuit problem: open, short, or failed solenoid. Start by measuring resistance across the purge solenoid - a $25 fix if the solenoid coil is open. See top-rated scanners on Amazon ↗
🗺️ Where Is the Problem?
Blueprint view - P0443 purge control valve circuit fault; electrical issue in EVAP solenoid circuit
These are statistical causes across ALL vehicles - your exact car may rank differently
For example, on a Honda 4-cyl the downstream O2 sensor causes P0443 64% of the time, but on a GM 5.3L V8 the catalytic converter is the cause 71% of the time. Get a probability ranking built specifically for your year, make, model, and mileage.
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🎯 Top Causes & Probability
55%
#1 - Most Likely
Failed EVAP Purge Solenoid
The purge solenoid's internal coil has failed - either open circuit (broken coil winding) or shorted. The PCM detects this by monitoring the current draw when it activates the solenoid driver. An open coil draws no current; a shorted coil draws too much. Resistance spec is typically 20–40 ohms - test with a DVOM.
🔩 Part
$20–$60
👨🔧 Labor
$40–$100
⚡ DIY Difficulty
Easy
25%
#2 - Check First
Open/Short in Purge Valve Wiring
Damaged wiring between the PCM and the purge solenoid - including broken wires, corroded connectors, or a short to ground or power - causes P0443. Inspect the wiring harness from the solenoid connector back to the PCM. Heat damage near the engine or firewall is a common cause.
🔩 Part
$5–$30
👨🔧 Labor
$60–$150
⚡ DIY Difficulty
Medium
12%
#3 - Less Common
Clogged Purge Valve
A purge valve mechanically stuck in one position can cause excessive current draw from the solenoid attempting to operate against a blockage, which the PCM detects as a circuit fault. Carbon or debris blocking the valve internally is the typical culprit. Replacement is the most practical solution.
🔩 Part
$20–$60
👨🔧 Labor
$40–$100
⚡ DIY Difficulty
Easy
8%
#4 -
PCM Purge Valve Driver Failure
Rarely, the PCM's internal driver circuit for the purge solenoid fails, preventing proper control signal delivery. This is diagnosed by confirming the solenoid and all wiring are good and the PCM is not outputting a proper control signal. PCM replacement is expensive - exhaust all other options first.
🔩 Part
$200–$800
👨🔧 Labor
$100–$200
⚡ DIY Difficulty
Hard
🚗 Most Affected Vehicles
🔧 Step-by-Step Diagnosis
- Test Purge Solenoid Resistance - Unplug the purge solenoid connector and measure resistance across the two solenoid terminals. Typical spec is 20–40 ohms. An open (OL) reading confirms a failed solenoid coil - replace the solenoid.
- Check for Power at Solenoid Connector - With key on, verify battery voltage is present at one of the solenoid connector terminals (the ignition-powered terminal). No voltage here indicates a blown fuse or wiring fault upstream of the solenoid.
📍 Find a Trusted Shop Near You
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Tips for Choosing a Shop
- Ask if they charge a diagnostic fee and whether it applies toward the repair
- Request a written estimate before approving any work
- Ask specifically about the part brand - OEM vs. aftermarket matters for this code
- Check Google reviews for recent mentions of the specific repair you need