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The check engine light is on and the PWM vacuum switching…

Customer Question
The check engine light...

The check engine light is on and the PWM vacuum switching valve is chattering on my 2006 Toyota corolla. The air filter is new and I replaced the mass flow sensor about a year ago. The code is PO171. What should I try and replace first?

Mechanic's Assistant: Does the light stay on, or does it blink?

The light stays on.

Mechanic's Assistant: Are you fixing your Corolla yourself? What have you tried so far?

Yes, I would like to fix it myself if possible. I have not tried anything to fix it yet. I looked and did not see any obvious cracks in the vacuum hoses but I have not crawled under to look at the EVAP canister under the car.

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

The car has 155,000 miles on it and I have never done anything to it other than replace the mass flow sensor last year. I unplugged the mass flow sensor with the check engine light on and the car stopped running so I think the mass flow sensor is still good.

Submitted: 3 months ago.Category: Toyota
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Answered in 10 minutes by:
12/26/2017
Toyota Mechanic: Pete, Auto Service Technician replied 3 months ago
Pete
Pete, Auto Service Technician
Category: Toyota
Satisfied Customers: 31,728
Experience: Over 17 years diagnosing and repairing automobiles various makes and models with some training and certifications.
Verified

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Can you post the year, model and engine liter size in your vehicle for me here?

Let me know so we can continue,thanks Pete.

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Customer reply replied 3 months ago
I thought this was a toyota service, I am not interested in paying for the service. Thanks.
Toyota Mechanic: Pete, Auto Service Technician replied 3 months ago

I am able to help with your vehicle here as I have worked on several Toyota models.Were you looking for something else?

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