What Does U0421 Mean?
A control module received invalid or corrupted data from the Ride Level Control Module over the network. This affects active suspension or ride height management systems that coordinate with other vehicle systems.
Common Causes
35%
Faulty ride level control module with internal circuit failure
30%
Damaged wiring harness or corroded connectors to ride level module
20%
CAN bus communication network issue affecting data transmission
10%
Electrical power supply problems to ride level control module
5%
Module software corruption or version incompatibility
Diagnostic Steps
1
Step 1: Verify ride level control module is present on network and responds to scan tool identification requests
2
Step 2: Inspect ride level control module location for water damage, corrosion, or connector issues
3
Step 3: Test voltage supply and ground circuits to ride level module with multimeter
4
Step 4: Check CAN bus communication signals and network integrity with oscilloscope or scan tool datastream
5
Step 5: Attempt module reprogramming or replace ride level control module if hardware diagnostics indicate failure
Estimated Repair Cost
$250 - $1,600
Parts + labor, varies by vehicle and location
A control module received invalid or corrupted data from the Ride Level Control Module over the network. This affects active suspension or ride height management systems that coordinate with other vehicle systems.
The most common cause of U0421 (Invalid Data Received From Ride Level Control Module) is: Faulty ride level control module with internal circuit failure
Typical repair costs for U0421 range from $250 to $1,600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Suspension may default to standard height or lose automatic leveling capability. Vehicle handling may be affected but remains drivable with reduced comfort.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0421 to identify the root cause.
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Quick Info
Category
Network
System
Active Suspension / Ride Height Control
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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