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U0652 — Lost Communication Egr Sensor B

Generic OBD-II · all makesNetwork / communication

OBD-II code U0652 indicates that a control module (usually the ECM) has lost communication with the EGR sensor 'B' on the vehicle's data network. This sensor is typically a smart sensor or module that reports exhaust gas recirculation position, and the fault means the expected data messages are not being received.

Symptoms

What causes it — most likely first

1. Faulty EGR sensor B (module)

The sensor itself has failed internally and is no longer sending data on the communication bus.

2. Open or shorted communication circuit

Wiring between the EGR sensor B and the control module is damaged, causing an open or short in the data line.

3. Poor electrical connection at EGR sensor B

Corrosion, loose terminals, or a backed-out pin at the sensor connector disrupts communication.

4. Loss of power or ground to EGR sensor B

The sensor module is not receiving proper voltage or ground, preventing it from communicating.

5. Faulty engine control module (ECM)

The ECM has an internal communication failure, but this is rare and should only be considered after all other causes are ruled out.

How it's diagnosed

  1. Scan for all codes and check for related communication U-codes or EGR circuit codes that may help isolate the issue.
  2. Visually inspect the EGR sensor B connector and wiring harness for damage, corrosion, or loose pins.
  3. Verify power and ground at the EGR sensor B connector using a multimeter.
  4. Check the communication bus wiring (e.g., LIN or CAN) for continuity, shorts to power/ground, and proper termination.
  5. Test the EGR sensor B by substituting a known-good unit or using a scan tool to command a self-test if supported.
  6. If all wiring and sensor tests pass, perform a network integrity test and consider a possible ECM fault as a last resort.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Can I drive with a U0652 code?

It may be possible to drive short distances, but performance issues and limp mode can occur. Prolonged driving may cause further damage or leave you stranded.

Is U0652 always caused by a bad EGR sensor?

No. While a faulty sensor is common, wiring issues, connector problems, or power/ground faults are also frequent causes. The ECM is rarely at fault.

Will replacing the ECM fix U0652?

Almost never. ECM replacement is often misdiagnosed for this code. The problem is usually the sensor, wiring, or connector. Only replace the ECM after exhaustive testing proves it is the cause.

What does 'sensor B' mean?

It typically refers to a secondary EGR position sensor, often found on engines with dual EGR valves or a second feedback sensor. The exact location varies by vehicle.