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P0698 OBD-II Trouble Code: Sensor Reference Voltage “C” Circuit Low

Check Engine Light

P0698 code definition

A P0698 trouble indicates that a problem has been detected by the Powertrain Control Module (PCM) or another control module in the sensor reference voltage "C" circuit.

What the P0698 code means

In the case of a P0968 code, a control module has detected an issue in the "C" circuit of the sensor reference voltage system. A module (most often the PCM) will have detected an irregular voltage level or connectivity problem relating to the electrical circuitry. The sensor reference voltage "C" circuit refers to a specific area of the sensor reference voltage circuit system. Some vehicle models may require multiple consecutive drive cycles with the reported issue in order to log the problem.

What causes the P0698 code?

  • Most instances of this trouble code are the cause of issues in the circuit-related wiring.

  • Corroded, broken, disconnected or faulty connectors and wiring can limit or disable the system.

  • In rare instances, a P0698 trouble code may be wrongfully reported as a result of a faulty control module. In this case, one or more modules may require reprogramming or replacement.

What are the symptoms of the P0698 code?

Depending on the severity of the circuit's electrical flow issue, the symptoms of a P0698 code can range from decreased fuel efficiency and underpowered engine performance to an outright failure of the engine to start. This code indicates that a voltage deficiency has been reported, but does not denote whether the deficiency itself is mild, severe or total. The ensuing symptoms will depend on the severity.

For the purpose of diagnosis, a trouble code and illuminated dashboard trouble light will come up to alert the operator to the problem.

How does a mechanic diagnose the P0698 code?

A P0698 code may be initially diagnosed by reading the trouble code via an OBD-II code reader. Because this code is often the result of an electrical connectivity failure, the wiring and electrical connectors should be thoroughly inspected for signs of fault, damage, corrosion and disconnection.

Each of the control modules that may have reported the concern should be tested according to the manufacturer's recommended method in order to verify them for signs of fault.

A specialized scanner (such as an Autohex) may be used to pinpoint control module concerns more easily. Due to the potentially high number of modules relating to the "C" circuit, specialized equipment can shave a lot of time from the diagnostic process.

Common mistakes when diagnosing the P0698 code

If the P0698 trouble code has been reported alongside other codes, it is possible that this code is indirectly the result of codes elsewhere in the system. As a general rule, trouble codes should be approached and fixed in the order in which they're reported.

How serious is the P0698 code?

Because a P0698 code does not specifically indicate how bad the voltage deficiency is, the seriousness will vary from case to case. However, due to the fact that the sensor reference voltage "C" circuit is necessary for the engine to function properly, it should be seen as an urgent and severe concern. Repairs are highly recommended as soon as they're made possible.

What repairs can fix the P0698 code?

  • Electrical connectors, wiring and any components related to the "C'" circuit should be replaced or repaired if they were cited as problems during the diagnostic stage.

  • The vehicle should be tested following any repairs. This will verify whether or not the trouble code has been solved properly.

Additional comments for consideration regarding the P0698 code

The "C" sector should be visually denoted somewhere along the circuit. Although the PCM is typically the control module that will report trouble codes of this nature, other modules may report a P0698 as well. These modules can include the body control module, anti-lock brake control module, fuel injection control module, turbo control module, anti-theft module, cruise control module, and climate control module.

Need help with a P0698 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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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