P0641 to P0643, P0651 to P0653, P0697 to P0699 and P0657 to P0659: sensor reference and actuator supply
One of the reference voltages the engine computer feeds to its sensors (A, B or C), or the supply it feeds to an actuator, is open, low or high.
SeverityHighCarrying on can cause expensive damage, so deal with it now.
Can you keep driving?Only as far as the workshopWhat does P0641 mean?
The engine computer feeds several sensors from shared, carefully regulated supplies, usually grouped into circuits A, B and C, and reads their signals against that reference. If one reference is pulled low by a short in any sensor or wire on it, every sensor on that circuit reads wrong at the same moment. That is why these codes usually arrive with a crowd of others, for the throttle, the pedal, the pressure sensors, and why the car may go into a protective mode with very little power.
What causes P0641?
- A short to ground in one sensor or its wire on the shared circuit
- A sensor with water inside it pulling the reference down
- A chafed harness where it touches the engine or a bracket
- A fault inside the engine computer, which is the least likely cause
What to check first for P0641
- Write down every code stored: they show which sensors share the failing circuit
- Unplug the sensors on that circuit one at a time and see whether the reference voltage recovers
- Inspect the harness for chafing, especially near the engine and the exhaust
- Look for water in sensor connectors after rain or washing the engine
Can you drive with P0641?
Drive only to a workshop and only if the engine pulls normally. With a reference voltage fault the throttle and pedal readings may be lost, which usually leaves the car in limp mode; have it towed if it barely moves or stalls.
Since May 2018 an engine warning light that stays on is a major defect at the MOT, so the car fails until the fault is fixed.
Codes on this page
12
- P0641Sensor Reference Voltage "A" Circuit/Open
- P0642Sensor Reference Voltage "A" Circuit Low
- P0643Sensor Reference Voltage "A" Circuit High
- P0651Sensor Reference Voltage "B" Circuit/Open
- P0652Sensor Reference Voltage "B" Circuit Low
- P0653Sensor Reference Voltage "B" Circuit High
- P0657Actuator Supply Voltage "A" Circuit/Open
- P0658Actuator Supply Voltage "A" Circuit Low
- P0659Actuator Supply Voltage "A" Circuit High
- P0697Sensor Reference Voltage "C" Circuit/Open
- P0698Sensor Reference Voltage "C" Circuit Low
- P0699Sensor Reference Voltage "C" Circuit High
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
