OBD-II trouble code
U045C: Invalid Data Received From Power Steering Control Module 'B'
A module is receiving messages from a second power steering control module ('B'), but the data is implausible or out of range. Electric power steering may reduce or suspend assist as a precaution — the wheel gets heavy but the car still steers. The link is alive; the content is wrong.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $1,200
- DIY difficulty
- Advanced DIY
Part of a 2-code family
U045C is one of 2 codes covering invalid data received from power steering control module. The letter is the slot number your manufacturer assigned — it is not a physical difference, and the same letter means different things on different makes. The diagnosis is the same for every code in the family.
Read the full guide for this family →What does U045C mean?
Vehicles with electric power steering (EPS) use a power steering control module to read steering torque and angle, drive the assist motor, and share steering data with the stability control system over the network. The 'B' designation identifies a second steering controller on vehicles that network more than one — for example some four-wheel-steer, redundant-steering, or heavy-duty platforms where front and rear or primary and backup steering are managed separately. U045C sets when a receiving module is still hearing from power steering control module 'B', but the data inside its messages is invalid — a reported torque, angle, or assist value that's out of range, implausible, or in conflict with what other modules observe. That distinguishes it from U015B, the lost-communication version, where the module goes silent altogether.
The system's response is protective. Steering assist acting on bad data could tug the wheel when it shouldn't, so EPS systems respond to untrusted values by reducing assist, disabling it entirely, or reverting to a default assist map — and stability features that depend on steering angle may switch off at the same time. The steering never disconnects: the mechanical linkage (or, on steer-by-wire systems, the redundant control path) remains, so the car still steers, typically with heavier effort that's most noticeable at parking speeds.
Causes follow the invalid-data pattern with a few steering-specific standouts. An uncalibrated or drifting steering angle sensor is a leading trigger — especially after an alignment, a steering or suspension repair, or a battery disconnect on vehicles that require a sensor relearn. Low system voltage is another classic, since the assist motor is one of the largest electrical loads on the car. Degraded torque sensors, corrupted or mismatched module software, and wiring or connector damage round out the list. Companion codes — steering angle sensor codes or a C-series EPS code — usually name the specific fault, and if both the 'A' and 'B' steering modules set invalid-data codes together, a shared voltage, ground, or bus problem is likely.
Common causes
- Uncalibrated or drifting steering angle sensor (common after alignment or battery disconnect)
- Low system voltage or a poor ground at the module (the assist motor is a large load)
- Degraded or out-of-range steering torque sensor
- Corroded, loose, or damaged connectors at the module
- Chafed or damaged bus wiring corrupting messages in transit
- Power steering module 'B' replaced without correct configuration
- Outdated, corrupted, or mismatched module software
- Internal power steering control module 'B' fault
Symptoms
- Heavier steering effort, most noticeable at low/parking speeds
- Power steering warning light or message
- Reduced or intermittently lost steering assist
- Stability control features that rely on steering angle disabled
- Companion steering angle or EPS codes stored alongside U045C
Diagnostic steps
- 1.Read all stored codes and note any steering angle sensor or C-series EPS codes.
- 2.Load-test the battery and verify charging voltage and the module's grounds — low voltage is a frequent trigger.
- 3.Confirm whether an alignment, steering/suspension repair, or battery disconnect happened recently and whether a steering angle relearn is required.
- 4.Perform the steering angle sensor calibration/relearn per the manufacturer's procedure.
- 5.Inspect connectors and bus wiring to the module for corrosion, looseness, and chafing.
- 6.Check whether the module was recently replaced without configuration.
- 7.If inputs, calibration, and wiring check out, suspect an internal module fault and verify with service data.
Repair cost
$90 – $1,200
Cost depends on the cause. A steering angle sensor calibration/relearn is often $75-$200. Repairing a connector, ground, or wiring fault is typically $90-$400. A steering angle or torque sensor replacement runs $150-$500. Reprogramming after a module replacement is usually $100-$300. Power steering control module replacement with programming is the higher end at roughly $600-$1,200. Confirm a calibration, sensor, or wiring fix before replacing the module.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with steering angle sensor service preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.