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DTC codes / U06xx · Network communication / U0652

U0652Lost Communication With EGR Sensor B

This code means the engine control module has lost the communication signal from the exhaust gas recirculation (EGR) sensor B, which is typically the sensor that monitors EGR flow or position on the EGR valve or tube. The computer sets U0652 when it expects data from that sensor over the controller area network (CAN) bus but receives no valid message for a set period, indicating a communication fault rather than a direct sensor performance problem.

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

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms besides the warning light
  • Rough idle or stumbling when the engine is cold, especially if the EGR valve is stuck open or closed
  • A slight decrease in fuel economy over time as the engine management defaults to a backup strategy
  • Intermittent hesitation or surging during light acceleration if the communication loss is sporadic
  • Failed emissions test due to an incomplete or failed EGR monitor
  • Other communication-related warning lights if the fault lies on a shared data bus

Common causes, most likely first

  1. Damaged, corroded, or disconnected wiring or connector at the EGR sensor B or its harness
  2. Faulty EGR sensor B itself, internally shorted or open and unable to transmit data
  3. Water or oil intrusion into the sensor connector causing intermittent communication
  4. A break or chafe in the CAN bus wiring between the sensor and the engine control module
  5. Failed engine control module or a faulty CAN transceiver within it, though this is less common
  6. Low battery voltage or a weak ground connection affecting the sensor's ability to communicate
  7. Aftermarket or improperly installed electrical accessories interfering with the data bus

How to diagnose and fix it

  1. Perform a visual inspection of the EGR sensor B connector and harness for corrosion, loose pins, or chafed wires, and clean or repair as needed
  2. Check for any related technical service bulletins (TSBs) or communication codes stored in other modules to narrow the fault to a specific circuit
  3. Use a scan tool to monitor live data for EGR sensor B and verify whether the signal is completely missing or intermittent while wiggling the harness
  4. Measure reference voltage and ground at the sensor connector with a multimeter to confirm the sensor is receiving power and ground
  5. Check the resistance and continuity of the CAN bus wires between the sensor and the engine control module, looking for opens or shorts
  6. Substitute a known-good EGR sensor B if the wiring and voltages check out, then clear codes and verify communication is restored
  7. If all external circuits and the sensor are good, diagnose the engine control module and its CAN transceiver, repairing or replacing only after confirming the fault

What most technicians overlook on U0652

  • A loose or corroded ground connection at the EGR sensor or engine block can cause a loss of communication that mimics a failed sensor, so always load-test grounds before condemning parts.
  • This code can be set by a low or failing battery because communication modules may drop offline during cranking, so check battery health and charging system output first.
  • Intermittent U0652 codes often appear after a repair that disturbed the harness near the EGR valve, so review recent service history before diving into complex diagnostics.
  • Some vehicles use a shared CAN bus for multiple sensors, and a fault in one sensor's wiring can pull down the entire bus, causing U0652 alongside other communication codes that may seem unrelated.
  • Replacing the EGR sensor without checking the connector terminal tension is a common misdiagnosis, as slightly spread pins can cause intermittent communication that disappears when the connector is reseated.

Can I keep driving with U0652?

You can usually continue driving with this code because the engine will default to a backup strategy, but avoid long trips or heavy loads until it is diagnosed. If the check engine light begins flashing or you notice severe drivability issues, stop driving and seek professional service.

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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