Diagnostic article Generic OBD-II
P06CA: cylinder 6 glow-plug rationality and inconsistent source wording
P06CA concerns cylinder 6 glow-plug rationality, with a cylinder reference conflict in the reviewed GM table.
Read before applying this article
Documented application
Documented 2025 GM diagnostic parameter monitor in 25OBDG04B.pdf; model, engine and calibration applicability require vehicle-specific confirmation.
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.
The P06CA dictionary definition and the system label in GM's table both point to cylinder 6. The same row's malfunction text unexpectedly names glow plug 4. This article retains that discrepancy rather than silently turning the table into a definitive cylinder-location instruction.
Supported operation of the monitor
GM describes an electrical-resistance check based on measured voltage divided by measured current. It is intended to detect a glow plug operating outside its specified range. The displayed parameter limits are 0.23 and 2.00, with no explicit unit attached to the expression on this page. The generic word “incorrect” therefore should not be taken as proof of an incorrect part number.
The plug must be commanded on for a calibrated interval. There must be no individual plug electrical fault or glow-plug voltage-feedback fault, and the glow system must be enabled. Engine operation excludes cranking; battery voltage and diagnostic enablement must also be acceptable.
Verification without overreading the row
The diagnostic uses 15 failing samples within 25, evaluated on a 100-millisecond task, and lists Type B reporting over two trips. A valid retest must exercise the powered resistance check after its prerequisites are met. A no-code result while feedback faults inhibit it is inconclusive.
Before using P06CA to select a physical plug or circuit, resolve the cylinder-label conflict through vehicle-specific service information. The row supports the resistance-monitor explanation but does not establish the cause, replacement requirement, or exact vehicle application. This documented limitation is why the article remains flagged for source review.
Source: GM monitor, PDF page 1255.
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
Cylinder 6 Glow Plug Incorrect
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