The front O2 sensor (located before the catalytic converter) on your 2.0L Honda CR-V (1997-2001) is a 4 wire sensor that comes equipped with an internal heater.
This heater will eventually fail and the fuel injection computer will set a P0135 trouble code. When this trouble code pops up, it usually means that it's time to replace the upstream O2 sensor.
In this tutorial, I'm going to explain how to test the heater element of the front O2 sensor and I'm also going to tell you where you can buy it and save some money.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Código P0135 (1997-2001 2.0L Honda CR-V) (at: autotecnico-online.com).
WIRING DIAGRAM: You can find the oxygen sensor circuit wiring diagram here:
- Oxygen Sensor Circuit Diagram (1997 2.0L Honda CR-V).
- Oxygen Sensor Circuit Diagram (1998-2001 2.0L Honda CR-V).
The rear O2 sensor heater element test can be found here:
Circuit Descriptions Of The Upstream Oxygen Sensor
The front oxygen sensor on the 1997, 1998, 1999, 2000, and 2001 2.0L Honda CR-V is a 4-wire oxygen sensor.
This O2 sensor is located before the catalytic converter and plays a crucial role in monitoring how effectively the engine cylinders are combusting the air/fuel mixture.
Of the four wires, one supplies power to the sensor's heater element, another serves as the heater element's ground, and the remaining two connect to the sensor's internal oxygen-sensing element.
Below you can find a brief description of the four wires of the O2 sensor.
NOTE: The front oxygen sensor's engine wiring harness connector has female terminals. The connector on the oxygen sensor itself has male spade terminals.
| Upstream Oxygen Sensor -1997 To 2001 | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | WHT | O2 Signal |
| 2 | GRN/BLK | O2 Signal |
| 3 | BLK/YEL | Heater Power (+) |
| 4 | BLK/WHT | Heater Ground (-) |
Where To Buy The Oxygen Sensor And Save Money
The O2 sensor isn't an expensive component and it's one that you can find just about at any auto parts store. The following links will help you to comparison shop and hopefully save you a few bucks.
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NOTE: If you're not sure if the above upstream O2 sensor fits your particular 2.0L Honda CR-V, don't worry, once you get to the site, they'll make sure the sensor fits, if not, they'll find you the correct one.
TEST 1: Making Sure The Heater Is Getting Power And Ground
To get your P0135 trouble code diagnostic under way, we're going to make sure that heater element inside the O2 sensor is getting power and Ground.
These two tests are done with your multimeter and involve testing the black with yellow stripe (BLK/YEL) and black with white stripe (BLK/WHT) wires of the front O2 sensor engine wiring harness connector.
If the O2 sensor is getting power and Ground, the next step is to check the resistance of the heater element in the next test section.
CAUTION: Since the O2 sensor is connected to your Honda CR-V's exhaust pipe, you need to test it with a completely cold engine. If your Honda CR-V has been running for any amount of time, let the engine cool down completely. If you have to raise your vehicle to access the O2 sensor, use jack stands.
IMPORTANT: The power and Ground tests are done on the engine wiring harness sensor connector. This connector has female terminals.
OK, this is what you'll need to do:
- 1
Locate the upstream oxygen sensor and disconnect it from its engine wiring harness connector.
- 2
Set your multimeter to Volts DC mode and turn the key ON but don't crank or start the engine (this will power up the O2 sensor's engine wiring harness connector).
- 3
Make sure that the BLK/YEL wire is feeding battery power.
Connect the red multimeter test lead to the BLK/YEL wire and connect the black multimeter test lead to the battery Ground (-) terminal.
Your multimeter should read 10 to 12 Volts DC. - 4
Make sure that the BLK/WHT wire is feeding Ground. This Ground is provided by the PCM.
Connect the black multimeter test lead to the BLK/WHT wire and connect the red multimeter test lead to the battery positive (+) terminal.
Your multimeter should read 10 to 12 Volts DC.
Let's take a look at your test results:
CASE 1: Your multimeter registered 10 to 12 Volts DC. This is the correct and expected test result.
Now that you have verified the basics, the next step is to make sure that he O2 sensor heater element resistance is within specification. For this test go to: TEST 2: Testing The Heater Element's Resistance.
CASE 2: The O2 sensor's heater is not getting power. There's a good chance that the O2 sensor's heater fuse is blown. So your next step is to check the fuse and if it's blown replaced it and retest.
CASE 3: The O2 sensor's heater is not getting Ground. The most likely cause of this is an open in the Ground wire between the O2 sensor connector and the fuel injection computer's connected.
Although it's beyond the scope of this tutorial to check the wiring, your next step is to do a continuity test on the Ground wire between the front O2's connector and the fuel injection computer.
