Sensor Reference Voltage "C" Circuit Open
Code P0697 indicates an open circuit in the Sensor Reference Voltage C circuit, which provides a stable 5-volt reference signal to engine sensors. When this circuit is open, affected sensors cannot communicate properly with the engine control module, causing performance and transmission issues.
What You Might Notice
- Transmission fails to shift between sport and economy modes
- Erratic or delayed transmission shifts
- Check Engine light illuminated
- Reduced engine performance or limp mode activation
- Possible sensor reading failures affecting fuel or ignition timing
Most Common Causes
- 1
Open connector or wiring
Disconnected, corroded, or damaged wiring in the sensor reference voltage C circuit. Check all connectors along the circuit for loose pins or corrosion.
- 2
Blown fuse or fusible link
A blown fuse or fusible link protecting the sensor reference voltage circuit prevents power delivery. Inspect the fuse box for a failed fuse on the reference voltage line.
- 3
Faulty system power relay
A defective relay that supplies power to the sensor reference circuit may fail to maintain voltage. Test or replace the relay controlling this circuit.
- 4
Bad sensor or internal circuit failure
A defective sensor with an internal open circuit or failed component in the powertrain control module can cause this code. Diagnosis requires testing individual sensors on the circuit.
How to Diagnose It
- 1
Check Open connector or wiring — Disconnected, corroded, or damaged wiring in the sensor reference voltage C circuit. Check all connectors along the circuit for loose pins or corrosion.
- 2
Check Blown fuse or fusible link — A blown fuse or fusible link protecting the sensor reference voltage circuit prevents power delivery. Inspect the fuse box for a failed fuse on the reference voltage line.
- 3
Check Faulty system power relay — A defective relay that supplies power to the sensor reference circuit may fail to maintain voltage. Test or replace the relay controlling this circuit.
- 4
Check Bad sensor or internal circuit failure — A defective sensor with an internal open circuit or failed component in the powertrain control module can cause this code. Diagnosis requires testing individual sensors on the circuit.
How to Fix It
- 1
Inspect and repair wiring connections
Visually inspect all connectors, terminals, and wiring in the sensor reference voltage C circuit for corrosion, damage, or looseness. Clean corroded connectors and reseat any loose connections.
- 2
Test and replace fuse
Locate the fuse protecting the sensor reference voltage C circuit in the fuse box. Test the fuse with a multimeter and replace it if blown or damaged.
- 3
Test and replace power relay
Use a multimeter to test the sensor reference voltage relay for continuity and proper operation. Replace the relay if it fails testing.
- 4
Test and replace affected sensors
Using a diagnostic scanner, identify which sensors are on the C reference voltage circuit and test them individually. Replace any sensors showing open circuit conditions or voltage readings outside 4.8-5.2 volts.
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