Diagnostic article Generic OBD-II
P233E: A low regulator supply circuit can create a high voltage drop across its driver
Understand the across-driver measurement behind GM P233E and why its low-circuit name does not mean every measured voltage must be low.
Read before applying this article
Documented application
2025 GM 04A documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P233E identifies a low supply-circuit condition for fuel-pressure regulator B's solenoid. The GM monitor evaluates the regulator's high-side driver while it is on. Its description uses a high voltage across that driver as evidence of a ground-directed fault.
Measurement reference changes the meaning of high and low
Voltage across a switching driver is not the same quantity as output voltage relative to ground. The source associates the on-state across-driver finding with less than 0.5 Ω between the regulator high-side connection and controller ground. That relationship explains why the generic low-circuit name can coexist with a high across-driver voltage observation.
Powertrain-relay voltage must exceed 11 V, run/crank must be active and engine cranking must be excluded. The controller confirms sixty-one failures within 122 samples, evaluated every 6.25 milliseconds, with one-trip reporting.
Keep the command and reference with the trace
An output measurement without its reference points cannot establish the documented criterion. Likewise, an off-state reading does not reproduce this powered-on assessment. Preserve driver command, supply state and the exact electrical status at the event.
The monitor does not directly diagnose low rail pressure or identify a defective pressure-regulator valve. It also provides no connector pin or safe stand-alone probing instruction. The applicable circuit and high-pressure fuel-system service procedures are necessary before locating the ground-directed path or choosing a repair.
Source and applicability
2025 GM 04A documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file. GM PDF, physical page 633.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Fuel Pressure Regulator B Solenoid Supply Voltage Control Circuit Low
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT