Fix P2185: Mechanic’s solutions that WORKED

The P2185: Engine Coolant Temperature Sensor 2 Circuit High code indicates an issue with the second engine coolant temperature sensor, particularly a high circuit signal. This sensor plays a critical role in monitoring the engine’s coolant temperature. When the signal from this sensor is higher than what the vehicle’s control module expects, it triggers this fault code.

P2185 quick overview

Meaning	P2185: Engine Coolant Temperature Sensor 2 Circuit High
Is it serious?	This code can indicate a serious issue that may affect engine performance and should be addressed promptly.
Possible causes	– Faulty Engine Coolant Temperature Sensor 2 – Wiring or connector issues for the sensor – Problems within the vehicle’s cooling system – Corrosion or poor electrical connections
How to diagnose?	Inspect ECT Sensor 2: Check if it’s properly installed and functioning. Evaluate Wiring and Connectors: Look for damage, corrosion, or loose connections. Analyze Coolant System: Examine for leaks or operational issues. Test Sensor Operation: Use diagnostic tools to check the sensor’s performance. Check Ground Connections: Ensure the sensor and related systems have proper grounding.

How to fix P2185 – learn from mechanics

I looked into P2185 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Volkswagen

Vehicle Information: 2006 Volkswagen Jetta TDI 1.9L

Issue + Repair History: Vehicle initially presented with MIL light on and codes P0671, P2185/08581, and 05658. Glow plugs and harness were replaced, resolving the P0671 issue. Remaining codes P2185/08581 and 05658 were related to the coolant temp sensor in the radiator outlet.

Other OBD2 Codes + Test Results:

• P0671: Glow Plug #1 or Harness
• P2185/08581: Coolant Temp Sensor in Rad Outlet
• 05658: Same as P0671, Glow Plug #1

Suggestions to Fix Issue:

• Replacing the glow plugs and harness for code P0671.
• Addressing the coolant temp sensor for the P2185/08581 code.

Final Fix: The issues were resolved by replacing the glow plugs and harness, and addressing the coolant temp sensor in the radiator outlet.

Case #2: Honda

Vehicle Information: 2006 Honda Civic LX 1.8L

Issue + Repair History:

• Initially, the Engine Coolant Temperature (ECT) sensor was replaced.
• The MIL lamp returned after a couple of weeks.

Other OBD2 Codes + Test Results:

• P2185: Engine Coolant Temp High Voltage
• P2183: ECT 2 Circuit Range
• P0111: Intake Air Temperature Sensor Circuit

Suggestions to Fix Issue:

• Inspect the connector for corrosion or damage.
• Check the readings of the engine temperature when cold using a scan tool.
• Consider the possibility of corrosion in the connector for the #2 temp sensor in the radiator.
• Assess the engine ground.

Final Fix:

• Replaced the temperature sensor in the radiator, which resolved the issue. The discrepancy between the two sensors’ readings was likely causing the fault.

Case #3: Volkswagen

Vehicle Information: 2012 Volkswagen Touareg TDI Executive 3.0L

Issue + Repair History:

• Initially had code 4238-P2185 for G83 temperature sensor and no heat.
• Replaced output hose temperature sensor and OE thermostat.
• Checked water pump impeller, which was metal and okay.
• After these repairs, the temperature was normal, but no heat was produced.

Other OBD2 Codes + Test Results:

• P2185

Suggestions to Fix Issue:

• Check the valve for the heater in the left wheel well area.
• Consider possible heater core blockage due to silicate compound.
• Flush the heater core with CLR and a garden hose to see if heating improves.
• Check for air in the system and bleed as necessary.
• Inspect for leaks, especially the heater crossover pipes.

Final Fix:

• The problem was the heater core shut-off valve located in the driver’s fender well.
• Bypassed the valve, and the heat worked fine.
• Replaced the valve with a new one from VW (part #7PP-819-810-A).
• After replacing the valve and purging the coolant system, the heating issue was resolved.

Case #4: Honda

Vehicle Information: 2009 Honda Accord EX-L 2.4L

Issue + Repair History:

• The car displayed a check engine light.
• Diagnostic revealed code P2185 for the Engine Coolant Temperature Sensor 2 Circuit High.
• Replaced the ECT sensor but the issue persisted.

Other OBD2 Codes + Test Results:

• Not mentioned in the description.

Suggestions to Fix Issue:

• Inspect wiring and connectors to the ECT sensor for damage or corrosion.
• Check for proper grounding of the sensor.
• Test the new ECT sensor for proper operation.
• Consider possible issues with the engine’s cooling system affecting sensor readings.

Final Fix:

• Discovered a fault in the wiring harness to the ECT sensor.
• Repaired the wiring harness, ensuring secure connections.
• After repairing the wiring, the code cleared, and the issue was resolved.

Case #5: Toyota

Vehicle Information: 2011 Toyota Camry LE 2.5L

Issue + Repair History:

• Engine light came on intermittently.
• Code P2185 indicated a problem with the Engine Coolant Temperature Sensor 2 Circuit High.
• Previous attempts to fix included coolant system flush and sensor replacement.

Other OBD2 Codes + Test Results:

• Additional codes related to the cooling system were present but not specified.

Suggestions to Fix Issue:

• Check the coolant level and quality.
• Examine the thermostat for proper functioning.
• Inspect the cooling system for any leaks or blockages.
• Reevaluate the installation and compatibility of the replaced ECT sensor.

Final Fix:

• Identified a malfunctioning thermostat causing irregular coolant flow.
• Replaced the thermostat with a new one.
• After thermostat replacement and system test, the engine light ceased, and no further codes were generated.

Advice	Description
Inspect Wiring and Connectors	Examine for damages or corrosion in wiring/connections to ECT Sensor.
Test ECT Sensor	Verify ECT sensor’s operation for accurate temperature readings.
Check Sensor Installation	Ensure proper installation and compatibility of ECT sensor.
Evaluate Cooling System	Inspect the cooling system for leaks, blockages, or malfunctions.
Verify Ground Connections	Ensure proper grounding for ECT sensor and related components.