DTC P0118 – How To Replace Engine Coolant Sensor

The OBDII trouble code of P0118 is indicating a serious problem with your Acura’s Engine Coolant Temperature sensor. This sensor relays the operating temperature of the engine to your Acura P75 or P72 ECU. Without this reference, your Honda or Acura ECU will not know what the temperature of the engine is, and will run roughly.

Today I’ll be showing you how to replace engine coolant sensor in a 1998 Acura Integra GS with a 1.8 liter B18 non VTEC engine in it. This DOHC engine has the Engine coolant Temperature (ECT) sensor located on the side of the cylinder head. To properly remedy your P0118 trouble code, it would help if you had a scan tool that was capable of reading real time values from your P72 or P75 ECU.

P0118 indicates a voltage range that is too high for your Honda ECU to understand. When your P72 or P75 ECU triggers the Malfunction Indicator Lamp (MIL) check engine light on your dash, it’s time to replace your ECT. Before you learn how to replace engine coolant sensor in a Acura Integra, you should disconnect the negative terminal to your battery.

Next, you will want to remove the spark plug wires, as this job of learning how to replace engine coolant sensor in your DOHC B18 requires the distributor to be taken off. Leave your spark plug wires connected to your distributor during the install, so you don’t mess up the firing order of your B18.

Remove the 12mm bolts that secure the distributor and lock in your B18 DOHC ignition timing. Carefully remove the distributor and unplug the main wiring harness that leads to the distributor itself.

Now with your distributor removed, you can now access and see your B18 Engine Coolant Temperature sensor, circled below.

Disconnect this two pin wiring harness, and you’ll want to replace both ECT as well as the coolant temp light sensor.

The one pin engine coolant sender is actually the sending unit for your engine coolant temperature. To replace your ECT with your new Acura unit, you will need part number 37870-PJ5-003 or 37870-PJ7-003 for the two pin coolant temperature sensor. You can also find this ECT under several GM part numbers as well, 213718 and 25174240.

The one pin spade engine coolant sender is part number 37750-PH2-014. Replace both senders using teflon tape and tighten to specification. Reconnect your B18 Acura Engine Coolant temperature sender connectors, and clear your P0118 OBDII trouble code. If your P0118 trouble code is not taken care of by using our how to replace engine coolant sensor DIY Guide, you will want to check the wiring of your connector.

The two pin weatherproof connector for your Acura Engine Coolant Temperature Sender is comprised of a green wire with yellow stripe, as well as a red wire with white stripe. Using a multimeter, you will want to put the black lead on the negative terminal of your battery.

Measure the Acura ECT for power – With the black lead of your multimeter on the negative terminal of your battery, check the red wire with white stripe for switched power. Switched power means you will need to put the key to the ON position but do not start the vehicle. With the key set to the ON position, you should have roughly 5 volts at this wire.

Measure the Acura ACT for ground – Flip the leads of your multimeter around, and check the green wire with yellow stripe for the low reference ground signal. If you do not have a ground signal here, ground this wire and check for continuity between the green wire with yellow stripe and the ECT wire of your Acura ( located on connector A for DOHC engines.)

You now know how to replace engine coolant sensor in a Acura Integra to fix your P0118 trouble code in your OBDII DTC system. If you have any questions about our DIY guide, please leave them for us below.