What Does P1488 Mean?
The auxiliary 5-volt reference voltage supplied by the PCM to various sensors is below specification. This indicates a short to ground in one of the sensor circuits or an internal PCM voltage regulator fault.
Safety Warning
Vehicle may have erratic operation, stalling, or fail to start. Not safe to drive until repaired as multiple sensors rely on this voltage for accurate readings.
Common Causes
35%
Short to ground in sensor signal wire causing voltage drop
30%
Failed sensor with internal short pulling down voltage
20%
PCM internal voltage regulator failure
10%
Corroded connector causing short between circuits
5%
Multiple sensors drawing excessive current on shared reference
Diagnostic Steps
1
Step 1: Measure 5-volt reference voltage at PCM connector; should read 4.5-5.5V with key on
2
Step 2: Disconnect sensors one at a time that use 5V reference (MAP, TPS, APP, etc.) and recheck voltage
3
Step 3: When voltage returns to normal, inspect wiring and connector of last sensor disconnected
4
Step 4: Check for pinched, chafed, or damaged wiring causing intermittent short to ground
5
Step 5: If all sensors and wiring test good, suspect internal PCM voltage regulator failure
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The auxiliary 5-volt reference voltage supplied by the PCM to various sensors is below specification. This indicates a short to ground in one of the sensor circuits or an internal PCM voltage regulator fault.
The most common cause of P1488 (Auxiliary 5 Volt Supply Output Too Low) is: Short to ground in sensor signal wire causing voltage drop
Typical repair costs for P1488 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may have erratic operation, stalling, or fail to start. Not safe to drive until repaired as multiple sensors rely on this voltage for accurate readings.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1488 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Engine Management System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
