Skip the auto shop - Our mechanics make house calls

Q: My Audi revs but will not drive in reverse. The ABS light is on and the brake light flashes on the dash. What could be the cause?

asked by on

Audi revs but will not drive in reverse...ABS light is on & Brake light flashes on the dash. What do you think I need?

My car has 120000 miles.
My car has an automatic transmission.

A: The transmission needs around 100 psi press...

The transmission needs around 100 psi pressure to operate all of the forward gears, but it needs 180-190 psi pressure for the reverse gears.

The transmission pump is designed to create 1000 psi of pressure and it is regulated by a pressure regulator located next to the pump. Check the wiring harness to the transmission and check the pressure to the transmission pump through the cooler lines. If the pressure is about 30 psi to 45 psi on the cooler lines and the wiring harness is in good condition, then the pump and the regulator is working correctly. In that case, the problem would now be within the transmission valve body (control module).

If the pressure is higher than 45 psi on the cooler lines, replace the pressure regulator solenoid in the transmission. If you need assistance, get a certified professional, such as one from YourMechanic, to replace the transmission oil pressure switch for your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Coolant leak despite water pump replacement

It sounds like you have already pinpointed the leak. I suggest having your radiator hose replaced as soon as possible since coolant loss can lead to engine overheating and extensive damage. A technician from your YourMechanic can easily do this...

Q: How long can a car run with a broken CV axle boot?

The axle CV joint boot is there to hold the lubrication for the joint and keep out dirt and water. Without replacement, the joint grease comes out first and collects dirt within. The dirt acts as sand paper and grinds...

Q: Coolant fan runs continuously? What can it be?

Hello. Most of the time on this vehicle the issue is caused by a failure in the fan control module. It typically has an internal short that causes this. I usually test the circuit to make sure that the computer...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...