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Amedee
Amedee, Toyota Technician
Category: Toyota
Satisfied Customers: 24806
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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What is error code 171 on a scion xa

Customer Question

what is error code 171 on a scion xa
Submitted: 5 years ago.
Category: Toyota
Expert:  Amedee replied 5 years ago.
Hello!

Is this a code p0171?
Customer: replied 5 years ago.
yes code p0171
Expert:  Amedee replied 5 years ago.
This is a lean code. you could have a bad mass air flow sensor. Or the snorkel from the mass air flow sensor to the throttle body could be ripped. Both are very common and can cause you vehicle to loose power along with many other drive ability issues. First look for cracks or rips or anywhere air can enter the engine that is not accounted for by the mass air flow sensor. Next comes the Mass Air Flow (MAF) sensor. This is a very important sensor input to the computer. It uses a hot wire sensing element to measure the amount of air entering the engine. The MAF sensor then outputs an analog voltage signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. If the sensor is bad than this air/fuel ratio will be off causing severe performance issues. In extreme cases, I have seen these two problems cause a no start condition. This input can also be used in determining transmission Electronic Pressure Control, shift and torque converter clutch scheduling. The check engine light may even pop on if the sensor is bad, the snorkel is ripped or a tube has fallen off. This will result in a lean condition.

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AMEDEE
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Customer: replied 5 years ago.
what is the replaement cost for the mass airflow sensor?
Expert:  Amedee replied 5 years ago.
Thanks for the accept!

According to my references, the O.E. part number for this mass air flow sensor is 222040D030. The price is $156.84 Of course you may be able to get it cheaper at a auto parts store, but I would not recommend it.
Customer: replied 5 years ago.
thank you
Expert:  Amedee replied 5 years ago.
You bet!