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Dan
Dan, Technician
Category: Audi
Satisfied Customers: 24209
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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A4 ABS light stays on

Resolved Question:

A4 ABS light stays on
Submitted: 7 years ago.
Category: Audi
Expert:  Dan replied 7 years ago.
This light usually comes on if you have a failed wheel speed sensor but these vehicels are common for the abs module to fail causing the same problem. You can backprobe the wires comming out of each wheelspeed sensor with the wheel lifted in the air and check for ac voltage as you spin the wheel. Whatever sensor does not put out voltage needs to be replaced if they all seeem to work it is likely the abs module. You can get a used abs module from www.car-parts.com sort by price and have them ship it to you. But before you replace any parts you would want to have the abs module checked for codes at one of your local shops that has a high end scantool that can access those codes. Let me know if you have questions, thanks.
Customer: replied 7 years ago.
i also have my ebrake light flashes when the ebrake is off, and some times my car will run rough like it is missing but not sure if is.
Expert:  Dan replied 7 years ago.
If the brake light is flashing and the abs light is on that points more towards the abs module being the problem which are extremely common on these vehicles. As far as the vehicle running rough at times that could be a few things different things and are unrelated. I would start out by replacing your spark plugs and you could clean your mass airflow sensor with approved cleaner from your local parts store. If your check engine light is on you can bring the vehicle to your local parts store and have them check the codes for free. Let me know if you have questions, thanks.
Customer: replied 7 years ago.
the check engine light is on and they said it was the seconddary air injection
Customer: replied 7 years ago.
that is what they said PO411 is the code
Expert:  Dan replied 7 years ago.
The secondary air injection would not cause the vehicle to run rough it is only for emissions. As far as the vehicle running rough, if it starter after you had the codes or got worse since then you may want to have the codes checked again to see if there is anything new. If not I would replace the spark plugs and clean the mass airflow sensor. As far as the P0411 code that could mean the combination valve, air solenoid valve, or catylitic converter has failed. It is a hard thing to diagnose without a high end scantool to commend the solenoids to turn off/on. You could start by replacing the combination valve then the air solenoid valve to see if that takes care of the problem before bringing it to a shop. And as far as the abs and brake light being on that is most likely caused by a failed abs module. You can get a used abs module from www.car-parts.com sort by price and have them ship it to you but it will need to be programmed at a dealership. Let me know if there is anything else I can do to help. Thanks
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