OBD-II code U0653 indicates that the powertrain control module (PCM) has lost communication with the EGR (Exhaust Gas Recirculation) Sensor C. This typically means the sensor or its circuit is not sending expected data, disrupting emissions control and engine performance.
The sensor itself may have failed internally, preventing it from communicating with the PCM. This is the most common cause.
Damaged, corroded, or loose wiring/connectors between the EGR Sensor C and the PCM can interrupt communication. Common in harsh environments.
An open or short in the signal, power, or ground circuit can prevent the sensor from transmitting data to the PCM.
If the EGR valve or another related component is malfunctioning, it may indirectly cause communication issues with the sensor.
Insufficient voltage or poor ground to the sensor can prevent it from operating correctly, leading to lost communication.
While uncommon, a PCM software glitch or internal fault could disrupt communication with the sensor. This is a last-resort diagnosis.
No, the PCM is rarely the cause of U0653. This code almost always points to a faulty EGR Sensor C, wiring issues, or power/ground problems. Replacing the PCM should only be considered after all other possibilities are exhausted.
While the vehicle may still run, driving with U0653 active can lead to reduced fuel efficiency, increased emissions, and potential engine performance issues. It’s best to diagnose and repair the problem promptly.
Use a scan tool to check if the sensor is communicating with the PCM. If no data is received, test the sensor’s power, ground, and signal circuits. If these are intact but the sensor still doesn’t respond, it is likely faulty.
Resetting the code may temporarily clear it, but if the underlying issue (e.g., faulty sensor or wiring) isn’t addressed, the code will likely return.