U1704

Code

Generic U — Network/User

Invalid Data Received from Control Module (Network Communication Error)

Brand: Generic

Type: U — Network/User

Views: UK: 22 EN: 38 RU: 28

AI status

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Page language: EN

Malfunction indicator lamp (MIL) or network warning lamp illuminated
Multiple modules reporting communication or data errors
Intermittent or permanent loss of specific vehicle functions (e.g., ABS, instrument cluster, HVAC)
Modules re-initializing or rebooting while driving
Stored related U-codes (communication errors) in multiple modules

Read all module fault codes with a capable scan tool; capture freeze-frame and network status
Check battery voltage and charging system under load (12.4–14.7 V typical) before testing
Visual inspection of wiring harnesses, connectors, and ground points for damage or corrosion
Inspect recent repairs or aftermarket installations that tapped into the network
Check for Technical Service Bulletins (TSBs) or software updates for affected modules
Monitor network error counters and message frequency with OE-level tool or CAN sniffer

Retrieve full DTC list from all modules and note which modules report U1704 or related U-codes.
Clear codes and attempt to reproduce; note if code returns and under what conditions (key on, start, driving).
Perform visual inspection of wiring, connectors, grounds, and any recent service areas; repair obvious damage.
Verify vehicle battery voltage and inspect charging system; correct low or noisy supply conditions.
Using a scan tool or CAN sniffer, monitor the bus for malformed frames, error counts, or conflicting node IDs.
Measure CAN High/Low voltages and waveform with an oscilloscope; look for missing recessive level, excessive noise, or improper termination.
Isolate the network section: disconnect non-essential modules or aftermarket devices one at a time to see if the fault clears.
If a suspect module is identified, check its power/ground/connector pinouts. Swap with known-good module only if allowed by OEM procedures.
Reflash or update module software/calibration if a software mismatch or known defect is suspected (follow OEM update procedure).
After repairs, clear codes and road-test to confirm the issue does not return; re-scan all modules for related codes.