Sensor Reference Voltage B Circuit High

Where it lives

For P0653, the circuit described runs through the sensor. The description of P0653 reports a fault at the sensor.

Check these first

• A short to voltage on the 5 volt reference B wire
• A failed sensor feeding voltage back on reference B
• Corrosion or chafing on reference B
• A weak ground on a sensor circuit
• A faulty ECM reference output

What to do next

1. Check the reference B voltage at each sensor
2. Unplug sensors one at a time to find the back feed
3. Inspect the wiring for a short to voltage
4. Repair the short on the reference B wire
5. Replace the ECM if reference B stays high with the circuit good
6. Clear the code and retest

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