P0608: Control Module VSS Output 'A' Malfunction
The P0608 code indicates a malfunction in the Vehicle Speed Sensor (VSS) output circuit 'A' within the powertrain control module (PCM). This means the PCM has detected an internal fault in its ability to process or output the vehicle speed signal, which is critical for transmission shift points, cruise control, and speedometer operation. The issue is typically internal to the PCM, though wiring or sensor problems can also trigger it.
1. Most Common Causes
- Faulty PCM (internal failure)
- Damaged or shorted wiring to VSS
- Faulty vehicle speed sensor (VSS)
- Corroded or loose electrical connectors
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Speedometer inaccurate or not working
- Transmission shifting erratically or stuck in gear
- Cruise control inoperative
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0608 and check for other codes.
Step 2: Inspect VSS wiring and connectors for damage or corrosion.
Step 3: Test VSS sensor output with a multimeter (AC voltage while spinning wheel).
Step 4: If wiring and sensor are good, suspect PCM failure; perform PCM reprogramming or replacement.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as transmission shifting issues can cause further damage. Short trips to a repair shop are okay if symptoms are mild.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. If the PCM needs replacement, it can range from $500-$1000 including programming. Sensor or wiring repairs are cheaper, around $100-$300.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.