Diagnostic article Generic OBD-II
P0526: A nearly absent fan-speed signal needs a valid speed expectation
Learn the GM P0526 feedback-rationality logic and the published time-unit error that prevents inventing an exact enable delay.
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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.
P0526 identifies a fan-speed sensor circuit fault. The cited GM monitor asks whether the feedback remains meaningfully above zero while the fan is expected to be rotating. That is a signal-rationality assessment, not direct proof that the fan's mechanical drive has failed.
The measured signal and the enabling expectation differ
The malfunction description uses a 4 rpm feedback boundary for considering the circuit operational. A separate enable refers to a minimum fan-speed threshold of 39 rpm. Those values serve different purposes: one judges the observed feedback, while the other helps establish an operating opportunity in which feedback should exist.
The diagnostic also requires supply of at least 11 V and no relevant speed-sensor or output-driver faults. It confirms 250 failures within 300 samples and uses two-trip reporting. A result outside the stated opportunity should not be compared directly with those counters.
Do not turn a misprinted unit into an invented delay
The table includes a time-above-minimum-speed prerequisite but prints its value with rpm units. Inspection of the original page confirms the inconsistency. This article therefore does not guess a number of seconds or use that cell as a reproduction instruction.
Preserve the measured speed, expected-speed condition and diagnostic eligibility. Further checks must establish whether the feedback is absent because of its signal path or because the assumed rotation is not occurring. The monitor summary alone cannot choose a sensor, harness or fan replacement.
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 449.
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
Fan Speed Sensor Circuit
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