P0443

Evaporative Emission Control System Purge Control Valve Circuit

P0443 is a generic OBD-II powertrain diagnostic trouble code: Evaporative Emission Control System Purge Control Valve Circuit. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0443
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P0443 means

P0443 is stored when the PCM detects an electrical fault in the EVAP purge control valve circuit. Unlike P0441 which flags an incorrect flow result, P0443 is specifically a circuit-level fault — the PCM cannot properly drive or sense the solenoid. The PCM typically applies a pulse-width-modulated ground to the solenoid's control side while monitoring current draw or voltage feedback; if the observed value falls outside the expected range (open circuit, short to ground, or short to voltage) the code is set.

Common electrical causes include a broken wire in the harness between the PCM and the solenoid, a corroded or pushed-back terminal at the solenoid connector, or an internally open or shorted solenoid winding. On some platforms the PCM driver itself can fail, especially after a voltage spike. The solenoid is often mounted close to the intake manifold and exposed to heat cycles that accelerate connector corrosion.

Because P0443 prevents the purge valve from operating, the EVAP system cannot vent canister vapors into the intake manifold. Over time this can lead to a saturated canister that vents raw fuel vapour to atmosphere, possibly triggering a secondary leak fault. Driveability impact is minimal in most cases.

Common causes

Most-frequently reported root causes when P0443 is logged.

  • 1
    Open circuit (broken wire) in the purge solenoid control or power supply wire
  • 2
    Short to ground or short to battery voltage in the solenoid circuit
  • 3
    Corroded, damaged, or backed-out terminal at the purge solenoid connector
  • 4
    Internally open or shorted purge control solenoid winding
  • 5
    Failed PCM output driver for the purge solenoid circuit
  • 6
    Chafed wiring harness contacting engine components or chassis ground
  • 7
    Water intrusion into solenoid connector causing intermittent open

Symptoms drivers notice

MIL illuminated after two consecutive failed purge monitor cycles
Fuel vapour smell if canister becomes saturated due to no purge
Possible secondary P0441 (no purge flow) or P0446 (vent control) codes
Minimal or no driveability impact in most cases
Potential slight rich condition at idle on extended no-purge operation

How to diagnose P0443

A typical diagnostic flow when this code is present.

  1. 1
    Read all stored codes and freeze-frame; note whether P0441 or other EVAP codes are co-present to distinguish circuit fault from flow fault
  2. 2
    Inspect the purge solenoid wiring harness from the PCM connector to the solenoid for chafing, melted insulation, or broken wires
  3. 3
    Unplug the solenoid connector and measure solenoid resistance across its terminals — most purge solenoids read 22–30 Ω; open or near-zero ohms indicates a faulty solenoid
  4. 4
    With the connector unplugged, back-probe the harness side: verify reference voltage (typically 12 V ignition feed) on the supply wire and that the PCM control wire shows the correct PWM signal when commanded on with a scan tool
  5. 5
    Wiggle-test the harness with the circuit live to catch intermittent opens; repair or replace any damaged wiring sections
  6. 6
    If wiring and solenoid test good, suspect a PCM driver fault — compare with known-good PCM data or refer to manufacturer TSBs before replacing the PCM

Related powertrain codes

Frequently asked questions

What is the difference between P0443 and P0441?

P0443 is an electrical circuit fault — the PCM cannot properly energise the purge solenoid. P0441 is a functional/flow fault — the circuit works but the EVAP system did not produce the expected flow result. P0443 often causes P0441 as a downstream consequence.

Can a bad purge solenoid cause P0443?

Yes. An internally open solenoid winding presents an infinite resistance to the PCM driver, which the PCM interprets as an open-circuit fault and sets P0443. Always measure solenoid resistance before condemning wiring.

Is it safe to drive with P0443?

The vehicle is driveable, but the EVAP system is non-functional. Continued driving with a stuck-off purge valve will eventually saturate the charcoal canister, potentially causing fuel vapour odour and additional codes. Repair promptly.

Could P0443 be caused by a bad PCM?

Rarely, but yes. A failed internal driver in the PCM can cause a P0443 even with a perfect solenoid and harness. Exhaust all external wiring and solenoid possibilities first; PCM replacement is a last resort and typically requires reprogramming.

Disabling P0443 in software

RaceTune can permanently disable P0443 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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