What Does P2508 Mean?
The ECM/PCM is detecting voltage on its power input circuit that is higher than specifications. This typically indicates a problem with the vehicle's charging system or power supply circuit to the computer.
Safety Warning
Overvoltage can damage multiple electronic modules and cause sudden engine shutdown or electrical fires. Vehicle should not be driven until repaired.
Common Causes
35%
Faulty voltage regulator in alternator causing overcharging
25%
Damaged wiring or poor ground connection to ECM/PCM
20%
Failing ECM/PCM with internal voltage regulation issues
15%
Corroded or loose battery terminals causing voltage spikes
5%
Aftermarket electrical accessories causing voltage irregularities
Diagnostic Steps
1
Step 1: Measure battery voltage with engine running; should be 13.5-14.5V (most vehicles)
2
Step 2: Check alternator output voltage under load; excessive voltage (>15V) indicates regulator failure
3
Step 3: Inspect ECM/PCM power supply circuit wiring and connectors for damage or corrosion
4
Step 4: Test voltage at ECM/PCM power pins with key on and engine running to confirm overvoltage condition
5
Step 5: Check for aftermarket electrical installations that may be backfeeding voltage
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The ECM/PCM is detecting voltage on its power input circuit that is higher than specifications. This typically indicates a problem with the vehicle's charging system or power supply circuit to the computer.
The most common cause of P2508 (ECM/PCM Power Input Signal High) is: Faulty voltage regulator in alternator causing overcharging
Typical repair costs for P2508 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Overvoltage can damage multiple electronic modules and cause sudden engine shutdown or electrical fires. Vehicle should not be driven until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2508 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electrical/Charging System
Difficulty
Type
Generic (SAE)
Recommended Tools
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