Diagnostic article Generic OBD-II
P0894: Slip during a Neutral Locked Turbine request
P0894 counts turbine movement during a specific Neutral Locked Turbine request in this Allison example.
Read before applying this article
Documented application
2009 General Motors diagnostic parameter file 09OBDG01 Allison TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established.
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 generic P0894 name is transmission component slipping. GM's 2009 Allison summary describes a narrower monitor: turbine slip during a Neutral Locked Turbine, or NLT, request from the engine controller. It must not be treated as a universal test of every clutch during ordinary gear changes.
Counted events belong to the current ignition cycle
An event is accumulated when commanded or attained range is NLT and turbine speed exceeds 50 rpm for more than three seconds. The failure decision uses at least three such events in the current ignition cycle. The source explicitly subtracts events carried over from previous cycles when forming that count.
This distinction matters when examining a lifetime or accumulated counter. A nonzero historical count does not automatically equal the current-cycle failure criterion.
The requested operating state is essential evidence
The controller must have the relevant NLT state and qualified power and engine conditions. Turbine rotation during a different range or request cannot simply be substituted into this monitor's rule.
Record the requested and attained state, turbine-speed evidence and event-count context through the proper transmission diagnostic equipment. The summary does not identify a specific worn clutch or authorize a rebuild solely from P0894. Verification should demonstrate correct behavior during the prescribed NLT assessment and completed monitoring. An ordinary shift that feels normal, or an erased code, may never exercise the condition that this particular check evaluates.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG01 Allison TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established. This explanation describes the documented monitor, not a universal repair procedure.
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
Transmission Component Slipping
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