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Home / DTC / U0650 — Lost Communication With Exhaust Pressure Control Valve A Sensor/Switch

U0650 — Lost Communication With Exhaust Pressure Control Valve A Sensor/Switch

Detailed page for trouble code U0650.

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U0650

Generic U — Network/User

Lost Communication With Exhaust Pressure Control Valve A Sensor/Switch

Brand: Generic
Type: U — Network/User
Views: UK: 18 EN: 35 RU: 20
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Page language: EN

Causes

  • Open or shorted wiring between the sensor/switch and control module
  • Corroded, loose or damaged connector at the sensor or module
  • Failed exhaust pressure control valve A sensor or switch
  • Faulty or intermittent CAN/LIN/serial communication bus (depends on vehicle)
  • Poor power or ground to the sensor/switch
  • Faulty control module (rare) or software fault

Symptoms

  • Malfunction indicator lamp (MIL) or system warning illuminated
  • Stored U0650 and possibly other network communication codes
  • Exhaust pressure control disabled — reduced emissions control or altered exhaust behavior
  • Reduced engine performance or limp-home mode on some vehicles
  • Diagnostic data for the exhaust pressure sensor absent or frozen
  • Occasional intermittent faults or no symptoms until repeated failures

What to check

  • Connect a scan tool and record freeze frame, stored and pending codes and module status
  • Check for other network codes (U0100, U0140, U0073, etc.) that indicate a broader bus issue
  • Verify live data availability for the exhaust pressure sensor/switch and note update rate and values
  • Inspect sensor connector and wiring for corrosion, bent pins, heat damage, or water intrusion
  • Backprobe sensor connector: confirm reference power (typically 5V or vehicle specific), ground continuity and signal presence while monitoring with scan tool
  • Measure continuity and resistance between sensor connector and module connector; check for opens or high resistance

Signal parameters

  • Typical sensor reference: 5 V (verify with vehicle-specific manual)
  • Typical sensor signal range (analog pressure sensors): ~0.5–4.5 V proportional to pressure — varies by sensor type
  • If a switch: signal may be digital (open/closed) or switched to ground/ignition — verify type in service manual
  • CAN bus typical voltages (idle/recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V; active states differ by ≈1 V on each line (verify 250/500 kbps per vehicle)
  • Termination: two 120-ohm resistors in parallel (≈60 ohm across CAN_H and CAN_L) — check resistance with power off
  • Message/update rate: sensor data should update regularly (varies — check manufacturer spec)

Diagnostic algorithm

  1. Retrieve codes and freeze frame; note if U0650 is permanent, pending or intermittent and record related network codes.
  2. Clear codes and perform a drive/activation test while monitoring live data for the exhaust pressure sensor/switch to see if fault returns.
  3. Inspect the sensor connector and harness visually for damage, corrosion, melted insulation, or water ingress; repair any obvious damage.
  4. Verify power and ground at the sensor connector with key ON (reference 5V or ignition feed depending on type). If power/ground missing, trace and repair supply or ground.
  5. Backprobe the signal wire and monitor signal on a scope or multimeter while actuating exhaust pressure control (if applicable) and while engine is running — confirm expected signal behavior or absence.
  6. Check continuity/resistance between the sensor connector and the control module connector pins with power off; repair open or high-resistance circuits.
  7. Check communication bus integrity: measure CAN_H/CAN_L voltages, resistance across bus (termination), and watch for other module communication failures. Repair shorts to battery/ground or replace damaged sections.
  8. Perform wiggle tests of the harness and connectors with a scan tool connected to reproduce intermittent faults; isolate the affected section.
  9. If wiring and power/grounds are good and communications are proper, replace the exhaust pressure control valve A sensor/switch with a known good unit and re-test.
  10. If replacement does not clear the fault, consult OEM software/ECU updates and suspect a module fault; consider module reprogramming or replacement as last resort.
  11. After repairs, clear codes and perform verification drive or functional test to confirm permanent fix.

Likely causes

  • Damaged harness or pin terminal caused by chafing, heat or moisture intrusion
  • Corroded connector at the exhaust pressure sensor or at the ECM/module
  • Failed exhaust pressure sensor/switch (internal electronics)
  • CAN/LIN wiring shorted to battery/ground or excessive bus load/faulty termination
  • Intermittent connection due to a broken wire or poorly crimped terminal

Fault status

⚠️ Status
Control module reports loss of communication with the Exhaust Pressure Control Valve A sensor/switch. The exhaust pressure control function may be disabled; MIL/diagnostic warnings set. Further inspection of wiring, connectors, sensor, and communication bus is required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

U0100 U0140 U0073 U0121 U0401
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