How To Test: P0116 OBD II Trouble Code (Honda 2.2L, 2.3L)

TEST 2: Checking Cooling Fan Motor Operation

There are several ways to test the operation of the cooling fan motors on your Honda (or Acura).

One is to disconnect the cooling fan motor and then apply power and Ground to its connector and see if it comes on. Another, and the one this test step will show you, is to use a scan tool to see if the fan motor comes on at 225 to 227°F (107-108°C).

Testing the cooling fan motor with a scan tool is the best option because we not only want to make sure the fan runs but that it's actually coming on when the cooling fan switch (located on the radiator's bottom tank) commands it to activate. Testing the cooling fan operation by observing the ECT temperature's value on the scan tool will let us do this.

NOTE 1: Your Honda is equipped with 2 fans. Only one comes on to cool the engine down when the A/C is off. When the A/C is on, both run.

NOTE 2: This test must be done with the A/C off.

OK, this is what you need to do:

1. 1

   With the scan tool still connected from the previous test.
   
   Scroll down to the ECT sensor's PID (COOLANT) and observe the temperature (see the photo in the image viewer).

2. 2

   Start the engine and let it warm up.
   
   IMPORTANT: Do not perform this fan motor test if in TEST 1 you found out that the thermostat is stuck closed. Replace the thermostat first.

3. 3

   The fan motor should come on when the ECT temp reaches 225 to 227°F (107-108°C).
   
   The engine cooling fan may come on a few degrees before and this is still normal.
   
   IMPORTANT: Turn off the engine if the ECT sensor temperature passes 227°F (108°C) and the fan has not come on. If this is your test result, then you now have clear indication that there's a problem with the fan or its control circuits (i.e. fan motor relay, fan fuse, etc.).

4. 4

   The cooling fan motor should turn off below 200°F (93°C) and the cycle will repeat itself as long as the engine is running and the A/C is off.

Let's interpret your test results:

CASE 1: The cooling fan came on and turned off at the indicated temps and cooled the engine down. This test result lets you know that the cooling fan is operating normally and cooling the engine correctly.

This test result also lets you know that the following components are OK and functioning correctly:

• Radiator fan relay.
• Radiator fan fuses.
• Radiator fan switch.

No further testing of the cooling fan motor or its circuits/components is needed.

CASE 2: The cooling fan DID NOT come on at the indicated temps. This test result confirms that your Honda is overheating due to a problem with the cooling fan motor or the cooling fan motor switch, or the cooling fan relay.

Although it's beyond the scope of this tutorial to test the fan motor itself, your next step is to test the fan motor. You can find the radiator fan motor test here: How To Test The Radiator Fan Motor (Honda 2.2L, 2.3L).

CASE 3: The cooling fan came on BUT DID NOT turn off or cool the engine down. This test result tells you that your Honda is overheating. Possibly due to a:

1. Bad thermostat (one that's stuck closed).
2. Blown head gasket.
3. Lack of coolant in the cooling system.

Where To Buy Your Honda's Parts And Save

I've been buying all of my parts online now for a while now and let me tell you its pretty convenient and the way to save money.

What really disappoints me about my local auto parts store is the fact that their parts are over-priced and they shouldn't be... after all they're made in China!

The fact that they're made in China doesn't bother me... it's just how much they are marked up!!!

The following links (above), once you click on them and go to their webpage, will verify if the part(s) fit your specific Honda or not. If they don't, they'll ask you for the specifics of your particular Honda and then find the right one(s) for you. It's that easy!

Final Thoughts On P0116

From personal experience, I can tell you that it's extremely rare for the ECT sensor to be causing a P0116 DTC on your Honda.

The 2 most likely culprits are:

1. Bad thermostat that's either stuck open or stuck closed or just missing.
2. Low coolant level.
3. Fan motors wired direct and over cooling.
4. Fan motor that's inoperative.

Now, if your Honda is also registering trouble codes P0117 ECT Sensor Circuit Low Voltage and/or P0118 ECT Sensor Circuit High Voltage along with code P0116, then you should troubleshoot and repair these first before replacing the thermostat or any other cooling system related component.

More Honda 2.2L, 2.3L Test Tutorials

If this tutorial was helpful/informative, you can find a complete list of tutorials here: Honda 2.2L, 2.3L Index Of Articles.

Here's a sample of the tutorials you'll find in the index:

• P0112 ECT Sensor Circuit Low Voltage (Honda 2.2L, 2.3L).
• P1129 MAP Sensor Signal Colder Than Expected (Honda 2.2L, 2.3L).
• P1128 MAP Sensor Signal Lower Than Expected (Honda 2.2L, 2.3L).
• P0108 Manifold Absolute Pressure (MAP) Circuit High Voltage (Honda 2.2L, 2.3L).
• How To Troubleshoot A No Start (Honda 2.2L, 2.3L).
• How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at: easyautodiagnostics.com).
• How To Bench Test A Starter Motor (Step By Step) (at: easyautodiagnostics.com).