U0121 on TOYOTA RAV4 — Lost Communication With Anti-Lock Brake System (ABS) Control Module A

Q: "What does U0121 mean on a TOYOTA RAV4?"

"U0121 indicates: Lost Communication With Anti-Lock Brake System (ABS) Control Module A. This is a network communication code. 2 TOYOTA RAV4 owners have reported this to NHTSA."

Q: "What are the most common causes of U0121 on TOYOTA RAV4?"

"Based on 2 NHTSA reports, the most commonly cited components are: Steering,Electrical System, Steering. These percentages are based on the component field in owner complaints."

Q: "Is U0121 serious on my TOYOTA RAV4?"

"Of 2 NHTSA reports for this code on TOYOTA RAV4, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic."

Q: "What should I do if my TOYOTA RAV4 shows U0121?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

What U0121 Means on Your TOYOTA RAV4

U0121 is a diagnostic trouble code indicating: Lost Communication With Anti-Lock Brake System (ABS) Control Module A. This code relates to the network communication system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

2 TOYOTA RAV4 owners have reported this issue to NHTSA across model years 2006. Most reports come from the 2006 model year. The most commonly reported component is Steering,Electrical System (50.0% of reports).

Real TOYOTA RAV4 Owner Reports

Source: NHTSA Complaints Database

"Steering froze up while leaving my driveway and p/s light came on. shut engine off and back on, but did not resolve. i recall at least one other time that steering locked up temporarily while at a stop. took to dealership for diagnostic as manual recommends. diagnostic shows dtcs u0105 and u0121."

— 2006 TOYOTA RAV4 owner · STEERING,ELECTRICAL SYSTEM · Filed 01/30/2019

"Heard abnormal mechanical rattle from the front end going over rough streets in san francisco. took vehicle in suspecting suspension issue to capitol toyota of san jose."

— 2006 TOYOTA RAV4 owner · STEERING · Filed 05/25/2012

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

2

'06

Common Causes on TOYOTA RAV4

Based on NHTSA complaint component analysis for this vehicle.

STEERING,ELECTRICAL SYSTEM 50%

STEERING 50%

What To Do Next

1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.

Frequently Asked Questions

What does U0121 mean on a TOYOTA RAV4? ▾

U0121 indicates: Lost Communication With Anti-Lock Brake System (ABS) Control Module A. This is a network communication code. 2 TOYOTA RAV4 owners have reported this to NHTSA.

What are the most common causes of U0121 on TOYOTA RAV4? ▾

Based on 2 NHTSA reports, the most commonly cited components are: Steering,Electrical System, Steering. These percentages are based on the component field in owner complaints.

Is U0121 serious on my TOYOTA RAV4? ▾

Of 2 NHTSA reports for this code on TOYOTA RAV4, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic.

What should I do if my TOYOTA RAV4 shows U0121? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.

U0121 on Other Vehicles

→ All codes reported on TOYOTA RAV4