A trouble code P0443: EVAP System Purge Control Valve Circuit Malfunction tells you that the EVAP purge solenoid isn't doing what is should be doing when the fuel injection computer commands it ON.
In this tutorial, I'll shed some light on what this trouble code means and some of the tests you can perform to find its cause (and solution) in case a loose gas cap is not the source of the problem.
Contents of this tutorial:
You can find this tutorial in Spanish here: Código P0443 ¿Qué Significa? (1999-2006 V8 Chevrolet Silverado, GMC Sierra) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
Chevrolet:
- 4.8L Chevrolet Silverado (1500, 2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
- 5.3L Chevrolet Silverado (1500, 2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
- 6.0L Chevrolet Silverado (2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
GMC:
- 4.8L GMC Sierra (1500, 2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
- 5.3L GMC Sierra (1500, 2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
- 6.0L GMC Sierra (2500): 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
What Does Trouble Code P0443 Mean?
A P0443: EVAP System Purge Control Valve Circuit Malfunction tells you that your Silverado or Sierra's fuel injection computer is activating the EVAP purge solenoid, but it isn't responding.
The EVAP purge solenoid is the one responsible for 'purging' the fuel vapors stored in the EVAP carbon canister.
How? By switching ON and allowing the fuel vapors to be sucked into the intake manifold plenum (when the engine is running and when it's commanded ON by the fuel injection computer).
Normally, the EVAP purge solenoid is in a closed state (OFF). In this state, it does not let fuel vapors pass thru' it and into the intake manifold.
Once the fuel injection computer commands it ON, the solenoid opens and the fuel vapors can pass thru' it and into the intake manifold.
Common Symptoms Of A P0443 Trouble Code
If the P0443 is being caused by a EVAP purge solenoid that's stuck closed, then it'll only cause the check engine light to illuminate and cause your Chevrolet Silverado (GMC Sierra) to fail an emissions test.
But if the EVAP purge solenoid is stuck open (when it should be closed), then you'll see one or more of the following problems:
- Rough idle.
- Engine has difficulty in starting.
Beyond a failed emissions test and the check engine light shining nice and bright on the instrument cluster, the EVAP system problem causing the P0443 trouble code usually does not cause any driveability issues.
What Does The EVAP System Do?
The purpose of the evaporative emission control (EVAP) system is to capture the fuel tank vapors and prevent them from escaping into the ambient air (the atmosphere).
The EVAP system, on the Chevrolet Silverado (GMC Sierra), consists of:
- Fuel tank.
- EVAP vent solenoid.
- Fuel tank pressure sensor.
- Fuel pipes and hoses.
- Vapor lines.
- Gas cap.
- EVAP emission canister (charcoal canister).
- Purge lines.
- EVAP purge solenoid.
What Causes A P0443 Trouble Code?
Generally, a P0443 trouble code is caused a bad EVAP purge solenoid. But it can also be the result of a loose gas cap (one that wasn't tightened enough after fueling the vehicle).
If a loose gas cap is not the problem, then the following problems could be causing the P0443 trouble code:
- A bad EVAP purge solenoid that is stuck open.
- A bad EVAP purge solenoid that is stuck closed.
- A wiring problem causing the EVAP purge solenoid a lack of 12 Volts.
- A wiring problem causing the EVAP purge solenoid to not get its activation signal.
How To Diagnose And Repair A P0443 Trouble Code
Repairing a trouble code P0443 usually involves bench-testing the EVAP purge solenoid to make sure that it's opening and closing.
To be a bit more specific: The EVAP purge solenoid is removed and tested to see if it's in its closed position.
Once removed, if the EVAP purge solenoid is in an open position (letting air pass thru'), then it's bad and needs to be replaced.
If the purge solenoid is closed (not letting air pass thru' it), then 12 Volts and Ground are applied to it from your Chevrolet Silverado or GMC Sierra's battery.
With 12 Volts and Ground applied to it, it should open and now let air pass thru' it.
If it does not open (with power and Ground applied to it), then the EVAP purge solenoid is bad and needs to be replaced.
More Chevrolet Silverado (GMC Sierra) Tutorials
You can find a complete list of V8 Chevrolet Silverado (GMC Sierra) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- Resistance Specifications Of The TAC Electronic Throttle Body.
- How To Test The GM Accelerator Pedal Position (APP) Sensor 2.
- How To Test The MAF Sensor (GM 4.8L, 5.3L, 6.0L, 8.1L).
- Blown Head Gasket Test (GM 4.8L, 5.3L, 6.0L).
If this info saved the day, buy me a beer!
