P0697 OBD-II Trouble Code: Sensor Reference Voltage “C” Circuit/Open

P0697 code definition

The P0697 code is a generic powertrain code related to computer output circuit issues, including an internal computer failure. In this case, the engine control module (ECM) or other supporting control module has detected a fault with the sensor reference voltage “C” circuit.

Codes related to the P0697 include:

• P0698: Sensor Reference Voltage “C” Circuit Low
• P0699: Sensor Reference Voltage “C” Circuit High

What the P0697 code means

A code P0697 will be stored when a fault is detected in the sensor reference voltage “C” circuit. The ECM may not be the only control module, including the body control module or fuel injection control module, to detect this particular fault. The “C” denotes a specific area of the circuit.

The 5-volt reference signal is sent to or from various control modules through the controller area network (CAN), which helps various components communicate in the vehicle. Your vehicle may require several drive cycles with this particular failure before a code is stored.

What causes the P0697 code?

Several problems may cause a P0697 code including:

• Damaged, open, or shorted wiring and connectors between control modules (including the ECM)
• Damaged, open, or shorted wiring and connectors between engine sensors
• Damaged or defective ECM

What are the symptoms of the P0697 code?

Symptoms of a P0697 code may include:

• Check engine or warning light may illuminate
• The vehicle may not start
• The vehicle may start, but with some difficulty
• The engine may idle roughly
• The vehicle may lack power during acceleration
• The engine may run roughly during normal driving conditions
• The engine may misfire
• Decreased fuel economy

How does a mechanic diagnose the P0697 code?

A mechanic may use several methods to diagnose a P0697 trouble code, including:

• Utilize an OBD-II scanner to check for a stored P0697 trouble code
• Use a complete wiring schematic specific to your vehicle’s specific make and model
• Visually inspect all related wiring and electrical components for damage
• Use a specialized scanner, such as a Tech II, to help locate the general area of the fault
• Use a memory saving device to ensure other controllers do not lose memory during reprogramming
• Use a diagnostic CAN scanner to see pin values and which control modules are activating
• Check for disconnected or defective or system grounds
• Check for any corroded or loose electrical connectors that may be increasing circuit resistance

Common mistakes when diagnosing the P0697 code

It is always recommended to diagnose and repair codes in the order in which they are stored, as subsequent codes may simply be a symptom of a larger problem.

How serious is the P0697 code?

Because a vehicle’s safe driving operation most likely will be impacted due to faults that store a P0697 code, this code is considered a potentially serious code. When this code appears, it is recommended to immediately take your vehicle to your local service center or mechanic for repair and diagnosis.

What repairs can fix the P0697 code?

Several repairs can fix a P0697 trouble code, including:

• Repairing or replacing any damaged electrical wiring or related components
• Replacing damaged or defective control modules as needed (varies depending on which control module may have detected the fault)
• Replacing damaged or defective ECM
• Clearing all codes, test-driving the vehicle, and rescanning to see if any codes reappear

Additional comments related to a P0697 code

Due to the complexity of trouble codes related to the controller area network (CAN), it is recommended to seek professional assistance in diagnosing and repairing your vehicle when this code is stored.

Additionally, remember that modules other than the ECM may also report a P0697. Be sure to visually locate the “C” sector along the circuit and thoroughly diagnose any possible causes for the fault prior to repair.

Need help with a P0697 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.