P0697
Sensor Reference Voltage "C" Circuit/Open
- Severity
- High
- Driving
- Drive only to a garage
An open circuit or general fault in sensor reference voltage "C". The module supplies a regulated reference - typically 5 volts - to a whole group of sensors, and each of them reports by returning a fraction of it. When that reference is lost, every sensor sharing it goes silent at once. Expect a long list of unrelated-looking codes: throttle position, pedal position, pressure sensors, temperature sensors, all faulting together.
Possible causes
- CommonOne sensor on the shared reference circuit failed internally and pulled the whole reference down
- CommonWiring shorted or chafed on the reference circuit
- CommonCorroded or water-ingressed connector on a sensor sharing the reference
- PossibleReference circuit shorted to earth or to another voltage
- PossibleFailed control module reference supply
What you might notice
- A long list of sensor codes at once
- Reduced power or limp mode
- Engine running badly or not starting
- Several gauges reading wrongly
- Check engine light on
What to check, in order
- Fix this before diagnosing any of the sensors. Every sensor code stored alongside it is a consequence, and replacing those sensors will change nothing.
- List which sensors have faulted. They all share reference "C", and that list is a wiring diagram of where to look.
- Unplug the sensors on that reference circuit one at a time with the reference voltage on a meter. When the reference recovers, the sensor you have just unplugged is the fault.
- Inspect connectors for water and corrosion, which is the most common way a reference gets pulled down.
- Check the harness for chafe damage where the reference circuit runs.
- Suspect the control module only after every sensor on the circuit has been eliminated.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Computer output circuits and control module
P0600P0601P0602P0603P0604P0605P0606P0607P0608P0609P0610P0611P0612P0613P0614P0615P0616P0617P0618P0619P0620P0621P0622P0623P0624P0625P0626P0627P0628P0629P0630P0631P0632P0633P0634P0635P0636P0637P0638P0639P0640P0641P0642P0643P0644P0645P0646P0647P0648P0649P0650P0651P0652P0653P0654P0655P0656P0657P0658P0659P0660P0661P0662P0663P0664P0665P0666P0667P0668P0669P0670P0671P0672P0673P0674P0675P0676P0677P0678P0679P0680P0681P0682P0683P0684P0685P0686P0687P0688P0689P0690P0691P0692P0693P0694P0695P0696P0697P0698P0699