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DTC codes / U04xx · Invalid data received from a module / U0442

U0442Invalid Data Received From ECM/PCM B

U0442 indicates that a control module on the vehicle's controller area network (CAN) received invalid or missing data from the engine control module (ECM) or powertrain control module (PCM), designated as 'B'. The receiving module expected a regular, properly formatted message from the ECM/PCM but instead detected corrupted, out-of-range, or absent data, so it flagged the communication fault.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaInvalid data received from a module

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) or a message on the driver information center
  • Often no symptoms besides the warning light, with the vehicle driving normally
  • Intermittent stalling, rough running, or reduced power if the ECM/PCM data loss affects other modules
  • Transmission may default to a limp mode or shift harshly because it relies on ECM/PCM data
  • Other dashboard warnings such as stability control or ABS lights may appear simultaneously
  • Remote start or certain convenience features may become inoperative

Common causes, most likely first

  1. Corroded, loose, or damaged wiring or connector pins on the CAN bus between the ECM/PCM and the receiving module
  2. Failing ECM/PCM power or ground connection causing intermittent data output
  3. Software or calibration issue in the ECM/PCM or the receiving module
  4. A malfunctioning ECM/PCM itself, though this is less common than wiring faults
  5. Electrical interference from a poorly installed aftermarket accessory or a failing alternator
  6. Open or shorted CAN bus circuit that intermittently disrupts communication

How to diagnose and fix it

  1. Record all stored codes and freeze-frame data, then clear codes and test-drive to see if U0442 returns
  2. Inspect the CAN bus wiring and connectors between the ECM/PCM and the module that set the code for corrosion, chafing, or loose pins
  3. Check ECM/PCM power and ground circuits with a multimeter under load to rule out voltage drops
  4. Perform a voltage drop test on the CAN bus lines to confirm proper signal integrity
  5. Verify the ECM/PCM has the latest software calibration and reflash or reprogram if a known issue exists
  6. Substitute a known-good ECM/PCM only after all wiring and power checks pass, then relearn and retest
  7. If the fault persists, consult factory service information for specific CAN bus topology and module communication tests

What U0442 really points to

  • U0442 is often set by a low battery or charging system problem that causes momentary voltage dips, corrupting CAN messages without any hard wiring fault.
  • A common misdiagnosis is replacing the ECM/PCM when the actual fault is a single chafed wire in the harness near a sharp bracket or heat source.
  • The code can be stored by any module on the network, not just the ECM/PCM, so always check which module reported it before starting diagnostics.
  • Aftermarket alarms, remote starters, or poorly spliced accessories can introduce noise on the CAN bus and trigger U0442 intermittently.
  • Some vehicles set U0442 when the ECM/PCM is busy or overloaded during a failed reprogramming event, so check for recent software updates first.

Can I keep driving with U0442?

The vehicle is generally safe to drive if it runs normally and only the warning light is on, but avoid long trips or heavy loads until the fault is diagnosed. If the engine stalls, runs poorly, or the transmission behaves erratically, stop driving and have the vehicle towed to prevent unsafe conditions.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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