P0698
Sensor Reference Voltage "C" Circuit Low
- Severity
- High
- Driving
- Drive only to a garage
Sensor reference voltage "C" is reading low - the regulated supply the module provides to a group of sensors has been dragged down, usually by a short to earth or by one failed sensor loading the circuit. Every sensor sharing that reference will now be reporting nonsense.
Possible causes
- CommonOne sensor on the shared circuit failed internally and is loading the reference
- CommonReference circuit shorted to earth
- CommonWater in a connector bridging the reference to earth
- PossibleChafed harness touching the engine or body
- PossibleFailed control module reference supply
What you might notice
- Many sensor codes at once
- Limp mode or reduced power
- Engine running badly or not starting
- Check engine light on
What to check, in order
- Do not diagnose the individual sensor codes. Fix the reference first and then see which codes actually come back.
- Unplug sensors on reference "C" one at a time while watching the reference voltage. Recovery when one is unplugged identifies it immediately.
- Look for water in connectors. A wet connector bridging the reference to earth is the classic cause and it is often intermittent with the weather.
- Check the harness for chafe points against the engine or body.
- Suspect the module only when every sensor on the circuit has been disconnected and the reference is still low.
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