P0C98: Sensor L temperature is inconsistent with its peers

P0C98 identifies hybrid/EV battery temperature sensor L range/performance. The 2018 GM test evaluates a discrepancy between L and an average of other battery-temperature inputs. A believable individual reading can still fail this relative check.

The difference, not the absolute temperature

The listed failure threshold is an absolute difference above 25 °C. Fifty failed evaluations out of 67, sampled every 25 milliseconds, meet the stated 1.675-second test. Reporting is Type B, two trips.

The comparison is inhibited by specified low-, high-, erratic-signal and battery-interface communication faults. This helps explain why fixing a basic circuit fault may be necessary before obtaining a meaningful performance result. An inhibited monitor is not a passing monitor.

Useful evidence for the next decision

Record L and the comparison temperatures together, retaining which direction the discrepancy takes. The code alone does not distinguish L reading too warm from too cold, prove which sensor is wrong or establish whole-pack overheating. Those conclusions require the actual measurements and the vehicle-specific diagnostic procedure.

Following repair, verify that the inputs are credible and the comparison is enabled and completes. A code clear without that information is incomplete. The letter L is a circuit identifier rather than a universal physical sensor location. Any access to internal battery sensing components requires qualified high-voltage personnel and the applicable safety process.

Source and applicability

This explanation follows the documented GM monitor, not a verified application to every vehicle with this code. Confirm the vehicle, reporting module and calibration in current service information. GM diagnostic table, physical page 925.