Short to ground on the auxiliary 5 volt supply wire, for example from chafed or damaged insulation; Faulty sensor on the shared 5 volt supply with an internal short pulling the voltage down; Corroded, damaged or water-contaminated connector at a sensor or at the control module; Wiring harness damage from rubbing, heat or previous repair work; Poor control module power or earth connections affecting the internal supply; Internal fault in the engine control module's 5 volt regulator.

P1488

Auxiliary 5 Volt Supply Output Too Low.

Pontiac
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
4: AreaAuxiliary emission controls
88: FaultThe specific fault in that area

What it means

P1488 means the engine control module saw the auxiliary 5 volt supply, a regulated reference voltage it provides to certain sensors, fall below its expected range. A short to ground, a wiring fault or a faulty sensor pulling the line down can cause this. Which sensors share this supply depends on the model and engine, so check the wiring diagram for the exact vehicle.

Symptoms

Malfunction indicator lamp on
Poor or erratic running, or hesitation under load
Reduced power or the car going into a limp-home mode
Rough idle or occasional stalling
Other sensor fault codes stored at the same time

Possible causes

Short to ground on the auxiliary 5 volt supply wire, for example from chafed or damaged insulationlikely
Faulty sensor on the shared 5 volt supply with an internal short pulling the voltage downlikely
Corroded, damaged or water-contaminated connector at a sensor or at the control modulepossible
Wiring harness damage from rubbing, heat or previous repair workpossible
Poor control module power or earth connections affecting the internal supplypossible
Internal fault in the engine control module's 5 volt regulatorrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, then look for other sensor codes that point to a shared supply.
Check the wiring diagram for the vehicle to find which sensors use the auxiliary 5 volt supply.
Visually inspect the harness and connectors for chafing, corrosion, moisture, bent pins and loose terminals.
With the ignition on, measure the voltage on the auxiliary 5 volt supply at the sensor connectors and compare it with the specification.
Unplug the sensors on the shared supply one at a time and see whether the voltage recovers, which identifies a sensor pulling the line down.
Check the supply wire for a short to ground with the module and sensors disconnected, using the resistance and continuity values from the service data.
Check the control module power feeds and earths, including voltage drop under load.
If the wiring and sensors are all good, confirm there is no updated software for the module before considering the module itself.

How to fix

Repair or replace the shorted or damaged section of wiring, using proper soldered and sealed joints.
Replace the faulty sensor that is pulling the supply down.
Clean, repair or replace corroded or damaged connectors and terminals.
Restore good power and earth connections to the control module.
Replace or reprogram the engine control module only once all wiring and sensors are proven good.

Can I keep driving?

Medium severity

The car may be driveable, but it could run poorly or enter limp-home mode, and the fault may get worse. Have it checked soon and avoid heavy loads or long journeys until it is repaired.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.