P1496

What it means

P1496 on a Pontiac means the engine control module has detected that its regulated 5 volt reference supply, which powers several engine sensors, is lower than expected. The module monitors this output internally and sets the code when the voltage sags below its limit. With the reference voltage low, sensor readings can become inaccurate and other sensor-related codes may appear alongside it.

Symptoms

• Check engine light on
• Rough idle or hesitation under acceleration
• Poor throttle response or reduced power
• Engine stalling or hard starting
• Erratic gauge or sensor readings on a scan tool
• Several unrelated sensor codes stored at the same time

Possible causes

• Short to ground in the 5 volt reference wiring shared by sensorslikely
• Faulty sensor (such as throttle position, MAP or pedal sensor, depending on model and engine) pulling the 5 volt supply downlikely
• Damaged, corroded or water-affected connector on a sensor or the control modulepossible
• Chafed or pinched harness shorting the reference circuit to ground or to another circuitpossible
• Poor control module power or ground connections affecting its internal regulatorpossible
• Internal fault in the engine control module's 5 volt regulatorrare

How to diagnose

1. Read all stored and pending codes and note the freeze frame data; look for other sensor circuit codes that share the 5 volt reference
2. Check for related service information for the specific model and engine to identify which sensors share the reference circuit
3. Visually inspect the engine harness and sensor connectors for chafing, corrosion, moisture and bent or pushed-out pins
4. Check the control module power and ground connections for security and voltage drop
5. With the ignition on, measure the 5 volt reference at the sensors and compare with the specified value
6. Unplug the sensors on the shared reference circuit one at a time while monitoring the voltage; if it recovers, the last sensor unplugged is faulty
7. If voltage stays low with all sensors disconnected, check the reference wiring for a short to ground with the module disconnected
8. Only once wiring, connectors and sensors are proven good, consider testing or replacing the control module

How to fix

• Replace the sensor that is pulling the reference voltage down
• Repair or replace the shorted or damaged section of wiring harness
• Clean or replace corroded or damaged connectors and terminals
• Restore good power and earth connections to the control module
• Replace or repair the engine control module if the internal regulator is confirmed faulty, following the correct programming procedure

Can I keep driving?

This code for other makes

• P1496Dodge5 Volt Supply Output Too Low
• P1496Jeep5 Volt Supply Output Too Low
• P1496KiaEGR Stepper Motor Malfunction Circuit 1 1.8L
• P1496Mitsubishi5 Volt Supply Output Too Low
• P1496Plymouth5 Volt Supply Output Too Low

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