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DTC codes / U06xx · Network communication / U0620

U0620Lost Communication With Exhaust Gas Temperature Sensor Bank 1 Sensor 2

U0620 is a communication fault where the engine control module (ECM) has lost the data signal from the exhaust gas temperature (EGT) sensor for bank 1 sensor 2, which is the downstream sensor after the catalytic converter on that bank. The ECM sets this code when it stops receiving the expected controller area network (CAN) messages from that sensor or its interface module for a calibrated period, not when the sensor simply reads an out-of-range temperature.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illumination of the check engine light or service vehicle soon message, often with no other noticeable symptoms besides the warning light
  • Reduced engine power or limp-home mode on vehicles that rely on EGT data for exhaust protection strategies
  • Poor fuel economy or altered regeneration behavior on diesel vehicles equipped with a particulate filter
  • Intermittent warning light that comes and goes with vibration, moisture, or temperature changes
  • Possible stored companion codes for other sensors on the same communication bus, indicating a shared wiring or module issue

Common causes, most likely first

  1. Damaged, corroded, or disconnected wiring and connectors between the EGT sensor and the ECM or its interface module
  2. Failed EGT sensor or sensor-integrated electronics that no longer transmit on the communication bus
  3. Open or shorted CAN bus wiring shared with other sensors, often from chafing or rodent damage
  4. Water intrusion into a connector or module causing intermittent communication loss
  5. Failed or intermittently failing module that acts as the gateway for the EGT sensor signal
  6. Loose or corroded ground connection for the sensor or module circuit
  7. Software or calibration issue in the ECM that misinterprets valid sensor messages

How to diagnose and fix it

  1. Record all stored and pending codes, then clear them and test-drive to confirm U0620 returns and to identify any companion codes
  2. Visually inspect the EGT sensor connector and the full harness run for corrosion, chafing, moisture, or rodent damage
  3. Check battery voltage and ground connections at the ECM and at the sensor or module mounting points
  4. Measure CAN bus resistance and voltage at the sensor connector to confirm the bus is intact and not shorted
  5. Substitute a known-good EGT sensor or interface module and clear codes to see whether communication returns
  6. If wiring and sensor are good, perform a module communication test with a scan tool to check for gateway or ECM faults
  7. Repair or replace the faulty harness section, connector, sensor, or module, then clear codes and verify with a road test

Communication loss is not always the sensor

  • A technician who replaces the EGT sensor first often finds the code returns because the real fault is a chafed CAN wire or a corroded connector pin shared with other sensors.
  • U0620 can be set by a weak battery or charging system fault that drops bus voltage momentarily, so always check battery health before condemning the sensor.
  • On some vehicles the EGT sensor communicates through a separate module rather than directly on the main bus, so a failed module can set U0620 even when the sensor itself is fine.
  • Intermittent U0620 that appears only in wet weather usually points to water intrusion at a connector rather than an electronic failure inside the sensor.
  • This code does not mean the exhaust temperature is actually too high; it means the ECM cannot hear the sensor, so do not chase overheating symptoms until communication is restored.

Can I keep driving with U0620?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy loads, towing, or long highway trips because the ECM may be running reduced-power or altered regeneration strategies without valid EGT data. If the engine enters limp mode or the warning light flashes, stop driving and arrange a diagnostic scan.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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