X204 ABS/ESC (Speed Sensor) Issues
 

Hi all,

2011 GLK (X204) displays ABS/ESC warning with those and traction control lights constant on.

Dealership diagnostic reported "5122 SIGNAL COMPONENT L6/3 (LEFT READ AXLE RPM SENSOR) IS IMPLAUSIBLE" and "7270 IMPLAUSIBLE VALUES OF RPM SENSORS, SPEED AT READ AXLE". They wanted to replace both rear sensors and charge $1000.

I took the vehicle home and replaced the left rear speed sensor (OEM part). Pretty confident I did it right, the swap wasn't too difficult. Cleared codes with new scanner. All lights return on short test drive. I scan and see a slew of codes:

C1122
NOT PRESENT
The signal of component "L6/3 (Left rear axle rpm sensor)" is implausible.

C3270
NOT PRESENT
Implausible values of rpm sensors : Speed at rear axle

U140D-00
CONFIRMED
An implausible wheel speed signal was received.

P0721
NOT PRESENT
Output Shaft Speed Sensor Circuit Range/Performance

P0720
NOT PRESENT
Output Shaft Speed Sensor Circuit

P1425
NOT PRESENT
The vehicle speed signal was not received.

P0521
PRESENT
The charge movement flap (cylinder bank 1) has a malfunction.


Does this indicate that I messed something up during the swap, or does it indicate a bigger problem? What should be my next troubleshooting step? Thanks!