P2184: coolant sensor 2 low circuit uses a configurable resistance channel

P2184 is an engine coolant-temperature sensor 2 circuit-low code. The reviewed GM row is explicitly labeled Diesel L6 ATM–LZO and uses a configurable temperature-sensor reading system. Physical sensor numbering should therefore not be inferred from the number of the internal measurement channel.

Function assignment determines the threshold

The table assigns the EngCoolantTempSnsr2 function to temperature sensor channel 1. Its low-resistance boundary is 48 ohms, shown at the 150°C reference. Other listed channels have different functions and limits, so their values must not be substituted merely because they appear in the same row.

The described failure mechanism is a short to ground in the sensor or signal circuit. The controller monitors resistance going below the expected range. This is an electrical-range diagnosis; a hot represented temperature does not independently establish actual coolant overheating.

Persistence and confirmation

The diagnostic must be enabled. The fault requires five seconds within a six-second window and is continuously sampled, with Type B reporting over two trips. One brief low reading is therefore not the complete documented qualification.

Verification should confirm the correct function-to-channel mapping and an eligible resistance-range check. A normal value on a different coolant-temperature channel cannot establish that sensor 2's monitor passed. The source does not identify the component's physical location, connector terminals or required repair. Apply the 48-ohm criterion only after confirming the vehicle uses this documented LZO temperature-sensing configuration and the corresponding service procedure.

Source: GM monitor, PDF page 791.