Short to ground or damaged wiring on the 5 volt supply circuit feeding one of the sensors; Faulty sensor pulling the 5 volt supply down (internal short in a sensor that shares the supply); Corroded, loose or water-damaged connector at a sensor or at the PCM; Chafed harness rubbing on the engine or bodywork, causing an intermittent short; Poor PCM power or ground connections affecting the supply output; Internal fault in the PCM 5 volt regulator.

P1488

Auxiliary 5 Volt Supply Output Too Low.

Plymouth
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 on a Plymouth means the engine control module (PCM) has detected that its auxiliary 5 volt supply output is too low. This is a second reference voltage the PCM provides to power certain sensors, and the PCM saw the voltage fall below the expected range, usually from a short or excessive load on the circuit or a fault inside the PCM itself.

Symptoms

Check engine light on
Poor or erratic engine running
Hesitation or poor throttle response
Reduced power or limp-home behaviour
Hard starting or stalling
Other sensor-related fault codes stored at the same time

Possible causes

Short to ground or damaged wiring on the 5 volt supply circuit feeding one of the sensorslikely
Faulty sensor pulling the 5 volt supply down (internal short in a sensor that shares the supply)likely
Corroded, loose or water-damaged connector at a sensor or at the PCMpossible
Chafed harness rubbing on the engine or bodywork, causing an intermittent shortpossible
Poor PCM power or ground connections affecting the supply outputpossible
Internal fault in the PCM 5 volt regulatorrare

How to diagnose

Read all stored and pending codes and note freeze frame data, paying attention to any other sensor circuit codes that appear alongside P1488.
Check the wiring diagram for your model and engine to identify which sensors share the auxiliary 5 volt supply, as this varies by application.
Visually inspect the harness and connectors for chafing, damage, corrosion, moisture or pushed-back pins at the sensors and the PCM.
Check the battery voltage and the PCM power and ground connections for good condition and low resistance.
With the ignition on, measure the voltage at the 5 volt supply circuit at the PCM and at each sensor connector, and compare it with the specification.
Unplug the sensors on the shared supply one at a time and watch whether the voltage recovers, which points to the faulty sensor.
Test the supply wiring for a short to ground or to other circuits with the PCM and sensors disconnected.
If wiring and sensors prove good and the supply stays low, check the PCM for a fault or an available software update before replacing it.

How to fix

Repair or replace damaged wiring that is shorted to ground or to another circuit.
Replace the sensor that is dragging the 5 volt supply down once it is confirmed faulty.
Clean or replace corroded or damaged connectors and terminals.
Secure and reroute the harness to stop it chafing.
Repair poor power or ground connections to the PCM.
Replace or repair the PCM only after all external causes are ruled out and the fault is confirmed to be internal.

Can I keep driving?

Medium severity

The car may be driveable, but poor running or limp-home mode is possible, and a lost sensor supply could cause stalling. Get it diagnosed soon and avoid long journeys until it is fixed.

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