P2508: ECM/PCM Power Input Signal High

P2508 is set when a supply input of the engine module reads above its permitted range. Ford documents it for the 2023 6.7 L Power Stroke diesel: the module checks its internal 5 V supply rail and flags P2508 once that rail exceeds 5.5 V, with continuous monitoring, roughly 5 s to mature, and the module awake (key on, running or after-run). The same group also blocks the reductant quality sensor test while P2507 or P2508 is present. On the 2014 BOSS 302S module Ford gives P2508 an M in the indicator column. A raised internal rail suggests a regulator fault inside the module or an external short to a higher voltage. P0563 reports excessive system voltage instead, P06A6 a sensor reference out of range. P2507 is the low partner.

Medium severity. Can I keep driving?It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

Symptoms

Check engine lamp
Other diagnostics such as the DEF quality test suspended
Erratic sensor values possible

Most likely causes

Internal 5 V regulator of the engine module defective
Supply or sensor wire shorted to battery voltage
Overvoltage from charging fault or jump start

What to check, in order

Start with the simplest. You can tick off each step.

Check the battery and grounds
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Clear the code and see if it returns
If it is a reference voltage code, disconnect sensors one at a time and see if the voltage recovers
Check whether a software update is available
Do not replace the control module without a full diagnosis

Good to know

Repair difficulty: hard
It can trigger limp mode.
It affects emissions.

What each character of P2508 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
5: Speed and idle
08: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2508?

It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

What causes code P2508?

The most common causes are: internal 5 V regulator of the engine module defective; supply or sensor wire shorted to battery voltage; overvoltage from charging fault or jump start.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.