U0690

Code

Generic U — Network/User

Lost Communication With EGR Temperature Sensor D

Brand: Generic

Type: U — Network/User

Views: UK: 8 EN: 18 RU: 12

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Page language: EN

Open, shorted or corroded wiring or connector for the EGR temperature sensor/module
Failed EGR temperature sensor/module (internal electronics)
Loss of sensor/module supply voltage or ground
Faulty CAN/LIN data bus (open, short to battery/ground, missing termination)
Intermittent connection due to water intrusion, chafing, or damaged pins
Blown fuse or relay that supplies sensor/module

Read all stored DTCs and freeze frame data with a capable scan tool; note if sensor/module appears on module list
Visually inspect the EGR temp sensor/module connector for corrosion, bent pins, water, or damage
Check fuses and relays supplying the sensor/module
Probe sensor/module supply and ground with key ON; verify proper voltage and a good ground
Check CAN/LIN bus lines at the sensor and at adjacent modules for correct idle voltages and presence of activity with a scope or bus analyzer
Backprobe connector to verify communication signals arrive at the module; compare to a known-good reference or other module

EGR temperature sensor output: typically a thermistor type — measured as resistance (common at 25°C: ~2–10 kΩ) or as 0–5 V on the controller input. Consult vehicle service manual for exact values.
CAN bus idle voltages (typical): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V common-mode; dominant/recessive differential signaling will show voltage swings when active. Use a scope or bus analyzer for waveform verification.
LIN bus (if used): wake and data pulses referenced to battery voltage; check against manufacturer spec.
Supply voltage to sensor/module: should be stable at battery/ignition supply (typically near battery voltage through appropriate circuitry).

Use a scan tool to confirm U0690 and list any additional communication or EGR-related codes. Note whether the EGR temp sensor/module is shown on the network.
Visually inspect the sensor/module connector and wiring for corrosion, bent pins, contamination, or mechanical damage.
Check and verify relevant fuses and relays. Replace if blown and retest communications.
With key ON (engine off), backprobe the sensor/module power and ground pins to verify presence of supply voltage and a solid ground.
Use an oscilloscope or bus analyzer at the module connector to check CAN/LIN lines for proper idle voltages and activity. If bus is silent, trace toward the gateway/ECU.
If bus signaling looks correct elsewhere but not at the sensor, perform continuity and resistance tests on the wiring between sensor and main harness/ECU (power removed). Repair any opens/shorts.
If wiring and power/ground are good but no communication occurs, suspect a failed sensor/module. If possible, substitute a known-good module or temporarily connect a known-good node to verify.
Check for related module faults or gateway issues; update or reflash module software if manufacturer bulletin recommends.
After repairs clear codes and road test while monitoring the scanner to ensure the U0690 does not return and the EGR system operates normally.
If the fault persists and all wiring, power, ground, and bus diagnostics are good, consider replacing the affected sensor/module or the gateway/ECU per service data.

⚠️ Status

Lost Communication With EGR Temperature Sensor D

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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