U0652

Code

Generic U — Network/User

Lost Communication With EGR Sensor B

Brand: Generic

Type: U — Network/User

Views: UK: 20 EN: 43 RU: 28

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Page language: EN

Causes

Open, short or high-resistance wiring between the module and the EGR sensor
Corroded, loose or damaged connector at EGR Sensor B
Faulty EGR sensor or local EGR sensor module
Loss of sensor reference power or ground
CAN/LIN bus fault or wiring short to battery/ground
Blown fuse or disabled power circuit for the sensor/module

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
No EGR Sensor B data or PID on a scan tool
Reduced engine performance, rough idle or hesitation (if EGR is commanded but not reported)
Possible limp-home mode depending on vehicle strategy
Other network communication DTCs present

What to check

Retrieve freeze frame and full DTC list. Note any other U- or P-codes.
Visual inspection of EGR Sensor B connector and harness for damage, corrosion, or water intrusion.
Verify battery voltage and main fuses; check fuse(s) supplying the EGR sensor circuit.
With key ON (engine OFF) backprobe sensor connector to confirm reference voltage (typically 5 V) and ground presence.
Use a scan tool to attempt live data read of EGR Sensor B PID and watch for intermittent updates or errors.
Check CAN/LIN bus health: measure CANH/CANL idle voltages and check for low resistance shorts to battery or ground.

Signal parameters

EGR position sensor analog output (if used): typically ~0.5–4.5 V across range (vehicle dependent)
Sensor reference voltage (if applicable): ~5 V nominal (verify with vehicle diagram)
Ground continuity: near 0 Ω to chassis ground under cold conditions; high resistance indicates issue
CAN bus idle voltages (typical): CANH ≈ 2.5 V, CANL ≈ 2.5 V; dominant state ~CANH 3.5 V / CANL 1.5 V (varies by system)
CAN/LIN data rate: commonly 250 kb/s or 500 kb/s for CAN; LIN is low speed (check OEM spec)

Diagnostic algorithm

Confirm code and record any related DTCs and freeze frame data. Clear codes and attempt to reproduce.
Perform a careful visual inspection at the EGR Sensor B connector and harness for bent pins, corrosion, melted insulation, or evidence of repair.
Using a scan tool, verify that EGR Sensor B PID is missing or frozen. Note whether other modules are missing on the network.
With key ON (engine OFF), backprobe the sensor connector: verify battery/reference voltage, signal presence, and good ground. Compare to expected values in service data.
If reference/ground are absent or incorrect, trace and test the power/ground circuits, check related fuses and relay(s). Repair wiring or replace fuse as needed.
If power and ground are good but no signal or communication, check continuity of the signal/CAN wires between the sensor connector and the controlling module. Repair any opens/shorts.
Use an oscilloscope to inspect the sensor signal or CAN bus waveform for noise, missing frames, or bus errors. Look for shorts to battery or ground on the bus.
If wiring and bus are good, substitute a known-good EGR sensor (or module) if available and re-test. Do not replace ECM/controller before verifying wiring and other modules.
If replacement sensor fixes the fault, clear codes and road test. If fault remains with new sensor and wiring verified, consider module failure and consult OEM procedures for module testing or reprogramming.
After repair, clear codes and verify no recurrence under all operating conditions.