How To Test Trouble Code P0141 (2001-2005 1.7L Honda Civic)

A P0141: secondary Heated Oxygen Sensor (Sensor 2) Heater Circuit Malfunction trouble code on your 1.7L equipped 2001-2005 Honda Civic (DX, EX, AND LX) indicates that the downstream O2 sensor's heater element is probably fried.

Fortunately, there's a very simple and easy way to find out if the downstream O2 sensor is bad (or not) and it involves 3 simple multimeter tests (no scan tool required).

ES You can find this tutorial in Spanish here: Cómo Verificar Código de Sensor de Oxígeno P0141 (2001-2003 Honda 1.7L) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 1.7L Honda Civic (DX, EX, LX): 2001, 2002, 2003, 2004, 2005.

Circuit Descriptions Of The Upstream Oxygen Sensors

As you're already aware, there are 4 wires coming out your Honda Civic's downstream O2 sensor.

We're only gonna' worry about the two wires (circuits) that provide power and Ground to the heater element.

The other 2 are the ones that provide the oxygen content info of the exhaust, to the PCM (Powertrain Control Module = Fuel Injection Computer).

Here are the circuit descriptions of the 4 wires (taking into account the engine code):

D17A1 Downstream Oxygen Sensor Pinout (2001-2005 1.7L Honda Civic DX, LX)
Pin	Wire Color	Description
1	GRN/YEL	PHO2S (Sensor Signal)
2	WHT/RED	SG2 (Sensor Ground)
3	BLK/WHT	Heater Element Power
4	BLK/YEL	Heater Element Ground

D17A2 Downstream Oxygen Sensor Pinout (2001-2005 1.7L Honda Civic EX)
Pin	Wire Color	Description
1	PNK	SG2 (Sensor Ground)
2	WHT/RED	PHO2S (Sensor Signal)
3	BLK/WHT	Heater Element Ground
4	BLK/ORG	Heater Element Power

Where To Buy The Oxygen Sensor And Save

Having the oxygen sensor's heater element fail is a very common problem and sooner or later, you'll need to replace one of them on your Honda Civic.

So, if you find, after testing the downstream oxygen sensor needs to be replaced, take a look at the links below. I think they'll save you some bucks:

NOTE: If you're not sure if the above downstream O2 sensor fit your particular 1.7L Honda Civic, don't worry, once you get to the site, they'll make sure the sensor is the right one, if not, they'll find you the right one.

TEST 1: Verifying The Heater Element Is Getting Power

The first downstream O2 sensor test that we're gonna' do is to make sure that it's heater element is getting power.

If your Honda Civic is a DX or an LX model (D17A1 engine), the BLK/YEL wire of the downstream O2 sensor engine wiring harness connector is the one that provides this battery power.

If your Honda Civic is an EX model (D17A2 engine), the BLK/ORG wire of the downstream O2 sensor engine wiring harness connector is the one that provides this battery power.

IMPORTANT: The O2 sensor and the exhaust pipe can get and stay very hot! Perform this test with a completely cold engine. Be careful and take all necessary safety precautions!

OK, this is what you'll need to do:

1. 1

   Locate the downstream oxygen sensor and disconnect it from its harness connector.

2. 2

   Locate the BLK/YEL (or BLK/ORG) wire (depending on your specific Honda Civic model) of the downstream engine wiring harness oxygen sensor connector.

3. 3

   With your multimeter in Volts DC mode, probe the BLK/YEL (or BLK/ORG) with the red multimeter test lead.
   
   Ground the black multimeter test lead directly on the battery negative (-) terminal.

4. 4

   With the Key On Engine Off (KOEO), this wire should have 10 to 12 Volts DC.

Let's take a look at your test results:

CASE 1: Your multimeter recorded 10 to 12 Volts DC. This voltage test result confirms that the heater element is receiving power.

The next step is to make check that the BLK/WHT wire, of the O2 sensor harness connector, is feeding Ground to the heater element. For this test, go to: TEST 2: Verifying The Heater Element Is Getting Ground.

CASE 2: Your multimeter DID NOT record the indicated voltage. Re-check that you're testing the correct wire and that the key is in the RUN position (but don't crank or start the engine) and re-test.

If you still don't see 10 to 12 Volts DC, then this test result tells you that the downstream oxygen (O2) sensor itself, on your 1.7L equipped Honda Civic IS NOT bad since without power, the heater element won't work.

Although it's beyond the scope of this article, the next step is to find out why this battery power is missing. On all models covered by this tutorial, the #4 10 amp fuse of the under-dash fuse/relay box is the one that provides power to this circuit and should be checked to make sure it's not blown.

TEST 2: Verifying The Heater Element Is Getting Ground

Whether your Civic is a DX, LX, or an EX model, the BLK/WHT wire of the downstream O2 sensor harness connector is the one that supplies the heater element with Ground.

To verify that the BLK/WHT wire is feeding the downstream O2 sensor with Ground, we'll do a simple voltage test with the multimeter in Volts DC mode.

IMPORTANT: The Ground supplied by the BLK/WHT wire is provided directly by your Honda Civic's PCM. Be careful and don't accidentally or intentionally short this wire to battery power, or you'll fry the PCM.

These are the test steps:

1. 1

   Locate the BLK/WHT wire of the O2 sensor's harness connector.
   
   NOTE: Remember, you'll test the wire that's on the engine wiring harness connector side and NOT on the O2 sensor itself.

2. 2

   Place your multimeter in Volts DC mode and:

   1. Connect the red multimeter test lead to battery (+).
   2. Probe the BLK/WHT wire of the O2 sensor's harness connector.
3. 3

   With the Key On Engine Off, this wire should have 10 to 12 Volts DC.

Let's take a look at your test results:

CASE 1: The multimeter registered 10 to 12 Volts DC. This test result lets you know that your 1.7L Honda Civic's downstream oxygen sensor's heater element is getting Ground.

So far you've confirmed that the downstream O2 sensor's heater element is getting both power and Ground. The next step is to check the heater element's resistance with your multimeter. For this test, go to: TEST 3: Testing The Heater Element's Resistance.

CASE 2: The multimeter DID NOT register 10 to 12 Volts DC. Re-check all of your connections and make sure you're testing the correct terminal.

If your multimeter still doesn't register the 10 to 12 Volts DC, then the most likely cause of this missing Ground is an 'open' in the BLK/WHT wire between your Honda Civic's PCM harness connector and the O2 sensor's harness connector.

TEST 3: Testing The Heater Element's Resistance

So far, you have done:

One: Confirmed that the downstream O2 sensor's heater element is being fed power by the BLK/YEL (or BLK/ORG) wire of the sensor's engine wiring harness connector.

Two: Confirmed that the downstream O2 sensor's heater element is being fed Ground by the BLK/WHT wire of the sensor's engine wiring harness connector.

The last test involves testing the O2 sensor's heater element's resistance with the multimeter in Ohms mode.

NOTE: The Honda manual calls for the O2 sensor to be at room temperature for the resistance test.

OK, this is what you need to do:

1. 1

   Locate the O2 sensor terminals number 3 and number 4 of the O2 sensor connector itself (not the engine wiring harness O2 connector).

2. 2

   With your multimeter in Ohms mode, probe terminals number 3 and number 4 of the O2 sensor itself.
   
   NOTE: The downstream O2 sensor for the D17A2 engine has female metal terminals. Avoid probing the front of these female terminals with the multimeter test leads or you run the risk of damaging them.

3. 3

   If all is OK, you should see about 10 to 40 Ω's on your multimeter.
   
   If the heater element is fried, your multimeter will show an open (usually indicated by the letters OL) or a number over 10 K Ωs.

Let's take a look at your test results:

CASE 1: Your multimeter confirmed the indicated resistance- This resistance test result tells you that your 1.7L Honda Civic's downstream oxygen (O2) sensor's heater is OK.

CASE 2: Your multimeter showed an open-circuit (OL). This confirms that the downstream (Bank 1 Sensor 2) O2 sensor's heater element is fried. Replacing the downstream O2 sensor with a new one will solve the P0141 trouble code lighting up the check engine light (CEL).

Here are some more specifics: Since you have:

• Confirmed that the downstream O2 sensor's heater element is getting power (TEST 1).
•      -AND-
• Confirmed that the downstream O2 sensor's heater element is getting Ground (TEST 2).
•      -AND-
• In this test you have confirmed that the heater element's resistance is out of specification.

... You can correctly conclude that the downstream O2 sensor on your 1.7L Honda Civic needs to be replaced with a new one.

More 1.7L Honda Civic Diagnostic Tutorials

You can find a complete list of diagnostics tutorials for your 1.7L Honda Civic in this index:

• 1.7L Honda Civic Index Of Articles.

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

• How To Test The MAP Sensor (2001-2005 1.7L Honda Civic).
• How To Test For A Blown Head Gasket (2001-2005 1.7L Honda Civic).
• How To Test The Crank Sensor (2001-2005 1.7L Honda Civic).
• How To Test Trouble Code P0141 (2001-2005 1.7L Honda Civic).