Code
U2003
DS
U — Network/User
Main wake-up not coherent / controlled main triggering request information coherence fault
Views:
UK: 4
EN: 5
RU: 5
AI status
Completed
Completed
100%
Causes
- Low or unstable vehicle battery voltage during sleep/wake sequence
- Open/shorted CAN or LIN wiring, poor termination or high impedance
- Faulty gateway, body control module (BCM) or other networked ECU
- Corroded/loose connectors or poor ground on network modules
- Software/firmware incompatibility or corrupted ECU software
- Aftermarket electronic device causing bus interference or wake requests
Symptoms
- Vehicle does not enter normal awake state or fails to respond to remote commands
- Intermittent or total loss of communication with one or several networked modules
- Central locking, keyless entry or remote start functions unreliable or inoperative
- Instrument cluster may not wake or displays multiple network-related warnings
- Diagnostic tool reports inability to communicate with certain ECUs or returns U2003
- Parasitic battery drain or abnormal sleep/wake behavior observed
What to check
- Read all stored and pending U-codes and related manufacturer fault history with OEM scanner
- Check battery state of charge and terminal condition; measure Vbat with vehicle off and during wake attempt
- Visually inspect connectors, wiring harnesses and grounds related to gateway, BCM and associated modules
- Verify CAN/LIN bus termination resistances and measure CAN-H/CAN-L voltages at rest and during wake
- Check for recent module replacements, software updates or aftermarket installations
- Attempt to reproduce the fault while monitoring live network traffic and wake-up messages
Signal parameters
- Battery voltage (Vbat) at key-off and during wake sequence (expected ~12.0–12.8 V idle, charging >13.5 V)
- CAN-H and CAN-L idle voltages (~2.5 V common mode) and differential amplitude (~2.0 V)
- Presence and ID of wake-up CAN messages (message frequency and timestamp when wake is requested)
- LIN wake line state or dedicated wake signal level if applicable
- Standby current draw (mA) to detect abnormal parasitic drain
- ECU response time and message acknowledgment rates during wake sequence
Diagnostic algorithm
- Use an OEM-capable scan tool: read U2003 plus any related network faults, note occurrence counts and timestamp/event data.
- Check battery voltage and health. Ensure battery is charged to specification and terminals are clean/tight. Repeat fault test.
- Inspect wiring and connectors for gateway, BCM and modules on the affected network. Repair any corrosion/damage.
- Measure CAN bus voltages and continuity. Confirm correct termination (typically ~60 Ω across CAN_H/L with key off).
- Capture bus traffic with a capable scope or CAN-USB logger while attempting wake. Look for missing or malformed wake messages and identify source node(s).
- Isolate modules: disconnect suspected nodes one at a time (following safe workshop procedure) to identify the module causing incoherent wake behavior.
- Check for recent software updates or module replacements. Reflash or update ECU software if confirmed or recommended by manufacturer bulletins.
- If a specific module (gateway/BCM) is confirmed faulty, replace or repair that module and reconfigure/recode as required.
- Clear codes and perform multiple wake/sleep cycles to verify repair and ensure no residual or intermittent faults.
Likely causes
- Weak battery or poor battery connections causing unreliable wake signal
- Faulty or improperly terminated CAN bus between gateway and BCM
- Defective gateway / main body ECU not forwarding or interpreting wake request
- Corroded connector at gateway or BCM producing intermittent signals
- Recent module replacement or software update with incompatible calibration
- Aftermarket alarm or remote start unit injecting spurious wake messages
Fault status
Status
Network coherence fault: main wake-up request and controlled triggering information mismatch detected. Code may be stored as active or historic depending on recurrence; further capture of wake events recommended.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email