OBD-II trouble code
U042C: Invalid Data Received From Chassis Control Module 'B'
A module is receiving messages from chassis control module 'B', but the data inside them is implausible or out of range. The connection is alive — the content is wrong. Can affect ride, handling, and stability features.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $1,100
- DIY difficulty
- Shop recommended
What does U042C mean?
This is the 'B' counterpart of U042B. On vehicles that split chassis control across more than one controller — for example a front/rear or left/right division of adaptive suspension and handling functions — chassis control module 'B' handles its portion of the ride and handling coordination. It reads motion and position sensors, arbitrates between suspension, stability, steering, and brake inputs for its domain, and reports its status to other modules over the network. U042C sets when a receiving module is still hearing from chassis control module 'B', but the data in its messages is invalid: a value is out of range, implausible, or contradicts what other modules see. The link is alive; the content can't be trusted. That is the key difference from a lost-communication code, which means the module has gone completely silent.
Because the fault is bad data rather than a dead bus, the causes cluster around whatever makes the module broadcast wrong information. A failing input — a ride-height sensor, an accelerometer or yaw/lateral-acceleration sensor, or a steering-angle sensor feeding the 'B' domain — can push the module into reporting values other modules reject. Since the chassis module aggregates several systems, a bad upstream signal is a common source. Low system voltage is a classic trigger, since module logic gets unreliable as voltage sags. The module's own software can be at fault if it is outdated, corrupted, or was never properly programmed after a replacement, and corroded connectors or chafed wiring near the wheels and suspension can corrupt otherwise-good messages in transit.
Symptoms depend on which data is invalid. You may see a check engine light plus chassis, stability, or suspension warnings, a ride that feels harsh or floaty because adaptive systems defaulted to a fixed setting, reduced torque vectoring or active roll control, or loss of automatic leveling — and because U042C names the 'B' controller, the effect may be localized to that controller's part of the chassis. The car generally stays driveable because the systems fall back to safe defaults and base braking and steering continue, but handling refinement and some stability-assist behavior can be reduced, so drive carefully until it is fixed. U042C is frequently a secondary code — read the full list, because a companion suspension, stability, or sensor code often names the real root cause.
Common causes
- Failing ride-height, accelerometer, yaw/lateral-acceleration, or steering-angle sensor in the 'B' domain feeding bad data
- Bad signal from an upstream stability, steering, or brake system the 'B' module aggregates
- Low system voltage or a weak battery/charging system
- Corroded connectors or chafed wiring near the wheels and suspension
- Outdated, corrupted, or mismatched chassis control module software
- Chassis control module 'B' replaced without proper programming or calibration
- Electrical noise or damaged bus wiring corrupting messages in transit
- Chassis control module 'B' internal fault
Symptoms
- Check engine light with chassis, stability, or suspension warnings
- Harsh, floaty, or inconsistent ride from adaptive systems stuck in a default setting
- Reduced torque vectoring or active roll control, possibly localized to one area of the chassis
- Loss of automatic ride-height leveling
- Companion suspension, stability, or sensor codes stored alongside U042C
- Vehicle driveable in a fallback mode with reduced handling refinement
Diagnostic steps
- 1.Read ALL stored codes first — U042C is often secondary to a suspension, stability, or sensor code that names the bad signal.
- 2.Confirm what the 'B' chassis controller governs on this vehicle, then focus testing on that domain's sensors and wiring.
- 3.Check battery and charging system voltage; low voltage is a common cause of implausible module data.
- 4.Use live data to compare the module's reported ride heights, accelerations, and steering angle against actual conditions.
- 5.Inspect ride-height sensor linkages and wheel-area wiring/connectors for damage and corrosion.
- 6.Trace any bad upstream sensor the 'B' module depends on, since the root fault often lives there.
- 7.Verify the module has the correct, current calibration, then address any companion codes before condemning the module.
Repair cost
$100 – $1,100
Cost depends on what is producing the bad data. A ride-height, acceleration, or steering-angle sensor typically runs $150-$450 installed. Correcting low voltage or a charging fault is $150-$600. Repairing wheel-area wiring varies with access. A module reflash is usually $100-$300, and chassis control module replacement with programming and calibration is the expensive case at $500-$1,100 — but that should only follow thorough diagnosis, since U042C is frequently a secondary code.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with module communication / can bus diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.