U068D

Code

Generic U — Network/User

Lost Communication With EGR Temperature Sensor A

Brand: Generic

Type: U — Network/User

Views: UK: 18 EN: 23 RU: 15

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Page language: EN

Open, shorted or corroded wiring or connector to the EGR temperature sensor
Failed EGR temperature sensor
Faulty EGR temperature sensor ground or supply circuit
Faulty engine control module (ECM) or another control module that relays the sensor data
Damaged or impaired vehicle communication bus (CAN/LIN) — open, short to Vb/GND, high resistance, missing termination
Intermittent connection (bent pin, water intrusion) or connector not fully seated

MIL (Check Engine Light) illuminated with U068D stored
Diminished or disabled EGR operation, which may cause increased NOx or degraded emissions performance
Possible reduced engine performance or limp-home strategy
Other communication-related DTCs present (bus errors, other module comm faults)
No valid EGR temperature PID/live data in scan tool for sensor A

Read all stored DTCs and freeze frame data; note any other communication codes or related EGR codes
Use a scan tool to monitor EGR temperature PID and communication bus status/messages
Visually inspect sensor connector and wiring for corrosion, damage, pin push-out, or water intrusion
Verify sensor supply voltage and ground at the connector with key on/engine off
Check continuity/resistance of CAN/LIN lines between sensor/module and ECM; verify correct termination resistance (~60 ohms across CANH-CANL for a two-terminator CAN)
Backprobe connector while monitoring data frames with a capable scan tool or scope

EGR temperature sensor analog range: typical -40°C to ~150°C (sensor dependent) reported as PID value when communicating
CAN bus idle common-mode ~2.5 V; CANH typically ~2.5–3.5 V, CANL ~1.5–2.5 V (differential signal when active)
Expected presence of regular CAN/LIN frames for EGR sensor PID at engine run or requested intervals
Termination resistance for CAN bus: approximately 60 ohms measured between CANH and CANL (two 120 Ω terminators in parallel)
LIN bus idle typically pulled to battery voltage via pull-up; active low frames — check for correct voltage levels and frame timing (baud rate depends on vehicle)

Confirm code and collect freeze frame and related DTCs. Note whether code is current or intermittent.
With a scan tool, verify whether EGR temperature PID A is present and whether any other modules report bus errors or bus-off states.
Visually inspect EGR temp sensor connector and wiring for damage, corrosion, pins pushed out, or water ingress. Repair or clean as needed.
Verify reference power and ground at the sensor connector with key on. If power/ground missing, trace and repair wiring, fuses, or relays.
Check continuity of CAN/LIN wires from the sensor to the module(s). Repair any opens/shorts. Verify correct termination resistance across CANH/CANL.
Use an oscilloscope or high-speed data logger to observe CAN/LIN signals at the sensor connector while the system is operating. Look for missing frames, excessive noise, incorrect voltage levels, or bus collisions.
If physical wiring and bus signals are good, substitute a known-good EGR temperature sensor (if available) and repeat communication check.
If sensor substitution does not restore communication, inspect/replace affected module connector or consider ECM/module testing. Reflash or update module software if manufacturer bulletin indicates.
After repairs, clear codes, perform a functional test of EGR operation and road test to confirm the fault does not return.
If intermittent, stress-test wiring by flexing harness, applying dielectric grease, and verifying long-term reliability before concluding repair.