P0445 is a common OBD II trouble code. It’s generic, which means that it has the same meaning for the Chevy Trailblazer as it would for any other vehicle. It indicates that there is a short circuit in the Evaporative Emissions Control (EVAP) System. P0445 is typically caused by a short circuit (as the code suggests) or by a bad purge valve (stuck open/closed).
Before you do anything, make sure the gas cap is on and sealed tightly. A bad gas cap can throw this code. It’ll usually be accompanied by other codes as well, such P0455.
Your vehicle’s Evaporative Emissions Control System is responsible for sending fuel vapor from the gas tank and sending it to the intake, where it can be burned. Otherwise these vapors are sent out into the air. You may notice a slight smell of fuel as well coming from your Trailblazer.
P0445 is typically caused by a short circuit (as the code suggests) or by a bad purge valve (stuck open/closed).
P0445 Symptoms: Chevy Trailblazer
There typically won’t be much in the way of noticeable symptoms associated with P0445 and your Trailblazer. Here are the most common ones:
- Check Engine Light– This is often the only symptom that you’ll see with this code.
- Gas Smell– If the purge valve is stuck shut, when the fuel vapor builds up it will escape into the air. You may smell gas.
- Minor Decrease in Fuel Economy– With your Trailblazer’s air/fuel minute being off, it may cause a minor dip in fuel mileage. It may not be perceptible to most people though.
Trailblazer P0445: Causes
P0445 indicates a problem with the a short in the wiring harness going to or from the purge valve solenoid, or in the solenoid itself.
Purge Valve Solenoid
The wiring in the purge valve solenoid can short out, which means it can’t respond to instructions from the ECM. It could also be a situation where it is stuck open or closed.
Wiring Issues
If the wiring harness from the PCM to the purge valve solenoid is frayed or shorted out, the purge valve won’t open and P0445 will be thrown. Take a look at the wiring harness plugged into the purge valve solenoid and see if it looks undamaged and that it is secure. You’ll also want to make sure that the purge valve is getting power to it at all.
How to Find a Short in a Car (Backyard Mechanic)
PCM
While it’s not nearly as likely as a wiring issue, or bad purge valve solenoid, or a bad PCM can trigger P0445.
P0445 Diagnosis: Chevy Trailblazer
A good code scanner can really help aid you in diagnosing P0445. You’ll be able to command the purge valve to open. When it opens, you should be able to hear it. If you don’t hear anything at all, you’ll need to check to see if the purge valve solenoid is getting any voltage. If it is, and the ground is good, it’s almost certainly the solenoid that is at fault.
If there isn’t voltage at the solenoid, you’ll need to go back and see if there is a wiring issue. You’re going to be looking for frayed and shorted wiring going to the solenoid.
Here’s a good YouTube video on how to diagnose P0440. but it’s completely applicable:
Conclusion: P0440 Chevy Trailblazer
P0445 can be somewhat tricky to diagnose. If there is anything you would like to add below, please leave a comment. Good luck fixing your Chevy Trailblazer!