What does it mean?
P1496 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: 5-Volt VREF Supply Voltage Too Low .
Symptoms
- MIL on, usually with several sensor codes set at the same time
- Poor drivability: hesitation, stumble, no start or limp mode
- Throttle response reduced, or the engine locked at a fixed idle speed
- Multiple live data values reading implausibly low at once
- Erratic instrument readings
Likely causes
- One sensor on the shared reference circuit shorted internally and dragging the reference voltage down
- Reference wire shorted to ground through chafed insulation
- Water or corrosion in a sensor connector bridging the reference pin to ground
- Harness damaged during previous engine or intake work
- Module internal reference regulator failure
- Poor module ground causing a low reference reading
- Aftermarket accessory tapped into the reference circuit and loading it
How to fix it
- List every stored code first; several sensors failing together points straight at the shared reference
- Measure the reference voltage at a sensor connector with the key on
- Unplug sensors on that reference one at a time and watch for the voltage to recover
- The sensor that restores the reference when unplugged is the shorted unit
- If the voltage stays low with all sensors unplugged, test the reference wire for a short to ground
- Check module ground points for corrosion and excessive voltage drop
- Repair the shorted sensor or wiring; consider the module only once the circuit is proven clean