P2184: Engine Coolant Temperature Sensor 2 Circuit Low

Coolant sensors are NTC thermistors: the hotter they get, the lower their resistance and voltage. P2184 therefore reports a signal from sensor 2 so low that it would mean an impossibly hot engine, typically a signal wire touching ground or a shorted sensor. GM's 2019 tables (19OBDG03D) set it when resistance drops below about 47.5 ohms, matching 150 °C, for 5 s within 6 s (Type B, MIL after two trips). VW's 2014 CC flags the radiator outlet sensor above 141 °C, the Touareg CNRB a voltage under 0.22 V. GM lists P2184 among the codes caused by a chafed engine harness in bulletin 21-NA-149. Because a hot reading is accepted as real at first, fans may run flat out. P2185 is the opposite fault, P2186 the erratic case.

Symptoms

• Check engine light after two drives on GM vehicles
• Radiator fans running at full speed
• Further codes and warnings if a harness is chafed

Most likely causes

• Signal wire of sensor 2 chafed through and touching ground
• Sensor 2 internally shorted
• Coolant or water in the connector bridging signal and ground

What to check, in order

Start with the simplest. You can tick off each step.

1. With the engine cold, check the coolant level; never do this when the system is hot
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Check the actual temperature in live data
4. Make sure the fan comes on when it should
5. Check the thermostat and connector
6. Measure the sensor and replace it if its readings do not make sense

Good to know

• Repair difficulty: easy
• It affects emissions.

What each character of P2184 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 1: Air and fuel
• 84: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2184?

Watch the temperature gauge. If it climbs or a warning appears, stop the car in a safe place and turn off the engine: overheating can cause serious damage.

What causes code P2184?

The most common causes are: signal wire of sensor 2 chafed through and touching ground; sensor 2 internally shorted; coolant or water in the connector bridging signal and ground.

Related codes

• P2185Engine Coolant Temperature Sensor 2 Circuit High
• P2186Engine Coolant Temperature Sensor 2 Circuit Intermittent/Erratic
• P2182Engine Coolant Temperature Sensor 2 Circuit
• P2183Engine Coolant Temperature Sensor 2 Circuit Range/Performance
• P0117Engine Coolant Temperature Sensor 1 Circuit Low
• P01E5Engine Coolant Temperature Sensor 3 Circuit Low

Sources

• gsi.ext.gm.com: 19OBDG03D Diagnostics
• static.nhtsa.gov: MC 10119356 9999
• static.nhtsa.gov: MC 10074008 2280
• static.nhtsa.gov: MC 10205552 9999

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.