P0608: The engine computer found a fault in the speed signal it sends out to other systems
Control module vehicle speed sensor output A malfunction
Severity: Severity not verified — if the car runs badly, have it inspected
The sources define the code but give no severity rating. Other systems that rely on the speed signal may misbehave, so have it checked.
P0608 in short
P0608 means the engine computer detected a fault in the vehicle speed signal it outputs to other systems. Likely causes are a wiring or connector fault, low system voltage, or an internal fault in the computer. Systems that use speed, such as cruise control or ABS, may act up, so get it checked.
The engine computer produces a vehicle speed output that other modules use. P0608 sets when it sees a malfunction in that output.
TroubleCodes.net says systems that depend on the speed signal, such as cruise control, automatic climate control, stability control and anti-lock brakes, may malfunction. Some vehicles may not start or may idle wrongly.
It lists harness and connector damage, low system voltage and an internal computer fault as the common causes.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Damaged, corroded or water-affected wiring or connectors
Common general cause- Why it ranks here
- TroubleCodes.net lists harness and connector problems first, and they are cheaper to check than the computer.
- What would change this
- Rises if inspection finds bent pins, corrosion or water. Falls if all connectors are clean.
Cause 2: Low system voltage or loose ground straps
Common general cause- Why it ranks here
- TroubleCodes.net names battery voltage below 9.5 V and loose grounds as a cause.
- What would change this
- Rises if voltage or ground checks fail. Falls if they are normal.
Cause 3: Internal fault in the engine computer
Possible — needs testing- Why it ranks here
- TroubleCodes.net points to the computer when voltage and circuit checks pass, so it ranks last.
- What would change this
- Rises only after wiring and voltage are cleared. Falls if either was faulty.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Check the fuses, junction boxes and connectors for damage, bent pins or corrosion.
IfDamage, corrosion or water is found
It meansWiring or connector fault is likely.
Points to: Damaged, corroded or water-affected wiring or connectors
IfEverything looks fine
It meansCheck voltage next.
Step 2: Have the battery and grounds tested, then the speed output circuit voltage measured with the computer connector off. TroubleCodes.net expects over 9.5 V.
Warning:Probing computer connectors can short pins and damage the module. Let a shop do it.
IfVoltage is low
It meansLook at circuit resistance, the battery and grounds.
IfVoltage is adequate
It meansThe computer itself is suspect.
Symptoms
- Check engine light
- Cruise control, climate control or stability control not working
- Anti-lock brake warning or ABS not working Gets more serious: stop and have it checked.
- Wrong idle speed or poor transmission engagement
How to fix
Parts and cost context
- Engine control module (ECM / PCM):Replacing the computer is the last step, after wiring and voltage are cleared.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0608 yet. The causes and tests above apply across vehicles.
Related codes
P0608 questions
Can I drive with P0608?
It may be possible, but systems that use the speed signal, including ABS, may not work properly. Have it checked soon.
Sources and review
- P0608 - Control Module Vehicle Speed Sensor Output A
- On-Board Diagnostic Trouble Codes (generic code title list)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error