2006 4 wheel drive base model codes are c1223 abs control sys malf, c1238 foreign object attached on tip of rear speed sensor RH, and c1336 zero point calibration of deceleration sensor undone. 2006 rav4 base model 4 cyl
The foreign object could be just some rust on the sensor or an indication it's beginning to fail. As I recall it was easily accessed after taking off the wheel. Removing it took some penetrating oil and patience. Then you can clean off any rust and clean up the hole it mounts in. Clear the code. If it comes back it's time to order an new sensor.
Originally vsc,abs,4wd,brake lights on. Tried a new gas cap,did not work. The cel light came on replaced cat converter and charcoal canister and reset code. , The shop also said right rear wheel speed sensor needed replacement. I replaced it cleaned the hole and sanded rust off top and now says a foreign object on tip of sensor. I flushed out cavity to see if any debris but none. Maybe sensor tone ring is damaged?
Sounds like some expensive repairs. Safe to assume the codes were reset afterward?
Also note that the wheel sensors codes, at least to my knowledge, come from the Skid Control ECU and need to be reset with an all-codes scanner or the 4-13 jumper method. Can't be done with an OBDII reader.