Diagnostic article Generic OBD-II
P20A3: purge-driver feedback remains high during the on command
GM P20A3 describes a short-to-power signature on the reductant purge low-side driver, evaluated while that driver is commanded on.
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Documented application
GM 2015 15OBDG04 Engine Diagnostics, cited reductant purge-driver high-voltage monitor only. Individual vehicle, engine, wiring and calibration applicability has not been established from this parameter 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.
P20A3 is the high-voltage electrical check of the reductant purge-valve low-side driver in this GM example. The decisive context is that feedback remains high while the driver is commanded on. The source associates that observation with a short-to-power condition.
High feedback is interpreted against command
A high reading without the command state is incomplete evidence. The electrical expectation with the driver off differs from the expectation when it is pulling the circuit low. This is why P20A3 cannot be diagnosed simply by borrowing the off-state criteria of P20A2.
The monitor requires ignition on, completed controller initialization and the specified battery-voltage qualification above 10.5 V. The fault must persist for three seconds, with monitoring at a 0.01-second rate when the listed enable and inhibition conditions are satisfied.
Separate circuit behavior from fluid performance
Preserve the driver's command, feedback and supply conditions. The short-to-power classification does not identify whether the cause lies in wiring, a connector or an internal component. The correct vehicle wiring procedure must isolate that distinction.
This electrical code also does not by itself prove that the purge or reverting valve failed to reduce fluid pressure. A pressure-response diagnostic addresses a different observation. The parameter table supplies no mandatory valve replacement or live terminal-test method. Professional verification must establish correct on-state feedback while respecting the reductant system's application-specific electrical and pressure precautions.
Source and applicability
GM 2015 15OBDG04 Engine Diagnostics, cited reductant purge-driver high-voltage monitor only. Individual vehicle, engine, wiring and calibration applicability has not been established from this parameter file.
General Motors source, physical page 195 · General Motors source, physical page 196
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
Reductant Purge Control Valve A Circuit High
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