P0608 code meaning
Control Module VSS Output A
What P0608 means
Many engine or powertrain modules turn the raw wheel or output-shaft speed into a cleaned-up vehicle speed signal and pass it on through their own driver – a square-wave signal whose frequency rises with speed – to the instrument cluster, cruise control, radio or steering. P0608 concerns output A: the module compares the commanded driver state with the actual line state and reports a short to ground or voltage, an open circuit or an internal driver fault, as CARB requires for output components. Output A is the first such output, usually the speedometer feed. If the speed sensor itself fails, P0500–P0503 set instead. No manufacturer table available to us gives thresholds; GM lists the code in older vehicles. On modern cars speed is shared over CAN, so the code mainly affects older vehicles with a hard-wired speedometer signal.
P0608 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor1 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0608
- Speedometer dead or jumping
- Cruise control not working
- Odometer stops counting
- Speed-dependent functions (steering, radio volume) disturbed
Common causes of P0608
- Most likelyShort or open in the output line A to the receiving module
- PossibleCorroded or spread connector pins at the module or receiver
- PossibleFaulty receiving module pulling the line to ground
- Less likelyInternal driver fault in the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine control moduleVehicle speed output wiringInstrument cluster
What each part of P0608 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| 08 | The exact fault in that area. |
What to do next
- Note P0608 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0608
What does P0608 mean?
P0608 means "Control Module VSS Output A". Many engine or powertrain modules turn the raw wheel or output-shaft speed into a cleaned-up vehicle speed signal and pass it on through their own driver – a square-wave signal whose frequency rises with speed – to the instrument cluster, cruise control, radio or steering. It is a generic code, so it means the same on every make.
Is it safe to drive with P0608?
P0608 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0608 fail an emissions test?
P0608 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0608 to fix?
Difficulty: medium. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P0608 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.