P2184Generic code

P2184 Code: Engine Coolant Temperature Sensor 2 Circuit Low

The P2184 code means the signal from coolant temperature sensor 2 is below its minimum value. The main effect is that the cooling fan may run all the time and temperature control becomes less precise. You can drive with caution while you watch the temperature gauge.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$20 to $150
Difficulty
Medium
System
Idle and Speed Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P2184 code means

Some engines have two coolant temperature sensors: one at the engine outlet and another at the radiator or somewhere else in the cooling circuit. With both, the computer controls the cooling fan and the electronic thermostat, and it can detect cooling system faults.

The sensor changes its resistance with temperature, and the computer measures the resulting voltage. A low signal is usually caused by a short to ground on the signal wire or by a missing reference voltage.

It is an NTC thermistor, which means its resistance drops as the temperature rises. A sensor guide shows how to test one.

To confirm it, unplug the component with the key on and watch what happens to the reading or the code. If the value jumps to the opposite extreme, the wiring is fine and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P2184 code symptoms

  • Check engine light on.
  • The cooling fan may run all the time, and temperature control becomes less precise.

Likely causes of the P2184 code

  1. Signal wire shorted to ground where the harness rubs against the engine, the chassis or a bracket.
  2. Shorted power reference. If several sensors fail at the same time, suspect the shared reference.
  3. Damaged sensor with an internal short.
  4. Connector with water or corrosion that creates a path to ground.

How to diagnose the P2184 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check power and ground with the key on: correct reference voltage and less than 0.1 V drop on the ground.
  4. Measure the signal with the connector plugged in and see whether it changes with the conditions.
  5. Do a wiggle test on the wiring with the scan tool in graph mode.
  6. Check the continuity of each wire to the computer (less than 1 ohm).

How to fix the P2184 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one.
  • Clear the codes and verify with a road test.

Clear the P2184 code and keep an eye on the temperature gauge during the road test. If it climbs above normal, stop the vehicle and let the engine cool down.

Technical reference data

  • Approximate resistance: 2 to 3 kilohms at 68 °F (20 °C) and 200 to 300 ohms at 194 °F (90 °C).
  • Signal: about 3 to 4 V cold and 0.5 to 1 V hot.
  • These are reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

The P2184 code is common on engines with an electronic thermostat and on engines with a sensor mounted in the radiator.

P2184 on BMW

Frequent on BMW engines with an electronic thermostat.

P2184 on Volkswagen

Frequent on Volkswagen engines with an electronic thermostat.

P2184 on Ford

Seen on several Ford engines that have the sensor in the radiator.

P2184 on GM

Seen on several GM engines that have the sensor in the radiator.

Frequently asked questions about P2184

Can I drive with a P2184 code?
Yes, while watching the temperature gauge. If it climbs above normal, pull over and stop.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wiring fail just as often as the sensor.
What does coolant temperature sensor 2 do?
Some engines have two coolant temperature sensors: one at the engine outlet and another at the radiator or elsewhere in the circuit. With both, the computer controls the fan and the electronic thermostat and can spot cooling system faults.
How much does it cost to fix P2184?
Roughly $20 to $150. A wire or connector repair sits at the low end, and a new sensor with labor is closer to the top.
What does the P2184 code mean?
It is a generic OBD2 code that means the signal from engine coolant temperature sensor 2 is below its minimum. It usually points to a short to ground or a missing reference voltage.
Will a P2184 code clear itself?
If the short was momentary, the light can go out after several drive cycles. A wire rubbing on metal will bring it back, so find the cause.
What is the most common cause of P2184?
A signal wire shorted to ground where the harness rubs against the engine, chassis or a bracket. A sensor with an internal short is the next most likely.

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