U2603

Code

LAND ROVER U — Network/User

CAN Bus Data Corruption Detected

Brand: LAND ROVER

Type: U — Network/User

Views: UK: 22 EN: 30 RU: 26

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Page language: EN

Causes

Damaged or chafed CAN wiring or harness (broken conductor, pinched cable).
Corroded, loose or contaminated CAN connectors or module terminals.
Missing, incorrect or damaged bus termination resistor(s).
Faulty module or ECU transmitting malformed frames.
Software/firmware bug in one of the networked modules.
Aftermarket electronic device improperly connected to the CAN bus.

Symptoms

Warning messages or icons on instrument cluster related to affected systems.
Intermittent or complete loss of function for one or more modules (e.g., ABS, traction, climate, infotainment).
Multiple communication-related DTCs present on scan tool.
Poor or no response from diagnostic module when connected to the network.
Strange or inconsistent subsystem behavior (random toggling, delayed responses).

What to check

Read and record all stored U- and related P-codes and freeze frame data with a capable diagnostic tool.
Inspect CAN connectors and harnesses visually and physically for corrosion, damage, water, or loose pins.
Measure CAN bus termination resistance between CAN_H and CAN_L with ignition off (typical ~60 ohms for a single closed network).
Backprobe CAN_H and CAN_L with a DVM/oscilloscope with ignition on and key in run; check idle voltages and differential waveform.
Use an oscilloscope to capture CAN signals while reproducing the fault; look for noise, missing recessive/dominant levels, error frames, or malformed packets.
Remove or isolate suspected aftermarket accessories or modules and re-scan.

Signal parameters

CAN_H idle ~2.5 V (recessive) — dominant pulses typically raise CAN_H to ~3.5–4.5 V.
CAN_L idle ~2.5 V (recessive) — dominant pulses typically drop CAN_L to ~1.5–0.5 V.
Differential voltage (CAN_H - CAN_L) recessive ~0 V, dominant ~2 V ±0.5 V.
Bus termination: two 120 ohm resistors in parallel ≈ 60 ohms across CAN_H and CAN_L (vehicle-specific networks may differ).
Typical bit rates: 500 kbps (powertrain/high-speed) or 250 kbps/125 kbps (body/interior) — verify manufacturer network speeds.

Diagnostic algorithm

Capture and document DTCs and freeze frame. Clear codes, operate vehicle to attempt to re-create the fault, and note conditions when code returns.
Inspect wiring and connectors for the modules listed in the freeze frame/scan tool. Repair any physical damage, corrosion, or poor pin retention.
Check termination resistance across CAN_H and CAN_L; correct missing or damaged termination. Repair harness as necessary.
With ignition on, measure static voltages on CAN_H and CAN_L at multiple connector points to identify abnormal voltage levels or a short to supply/ground.
Use an oscilloscope to monitor CAN bus while exercising affected functions; look for error frames, truncated frames, excessive noise, or modules transmitting malformed frames.
Isolate the fault by disconnecting modules one at a time (or segmenting the bus) while observing the bus for disappearance of corrupted frames. When corruption stops, suspect the last disconnected module or its harness.
If a particular module is implicated, check for software updates or recalls, reflash/update module software per manufacturer procedures, and re-test.
Replace or repair the faulty module/wiring/connector as indicated by isolation testing. After repair, clear codes and verify fault does not return during road test and repeat test conditions.
Document repair and any parts replaced. If intermittent, consider environmental stress testing (heat/cold/wet) to confirm repair.

Likely causes

Intermittent connector contact at one of the modules on the affected CAN network.
Open or shorted CAN high/low pair or incorrect termination (not ~60 ohms across CANH-CANL).
One module repeatedly transmitting corrupted frames due to internal failure or corrupted flash.
Recent repairs, connector disturbance or aftermarket installation introduced wiring damage.
CAN bus voltage levels outside normal ranges due to power/GND problem or high noise.

Fault status

⚠️ Status

Stored communication fault indicating CAN data corruption detected on the network. The fault sets when received frames fail integrity checks (CRC/format) or contain invalid data patterns. May be intermittent or permanent depending on wiring, connector, or module condition.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-4.0 hours

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