Front Oxygen Sensor Heater Tests (2002-2003 2.5L Nissan Altima)

TEST 2: Testing The Heater Element's Resistance

So far you've confirmed that your 2.5L Nissan Altima's front O2 sensor's heater is getting power. In this last test section, we are going to make sure that the heater element resistance is within specification.

The 2002-2003 2.5L Nissan Altima O2 sensor heater's resistance specification is 2.3 - 4.3 Ohms at room temperature.

These are the test steps:

1. 1

   Disconnect the O2 sensor from its electrical connector. the O2 sensor should be completely cold for this test.

2. 2

   Place your multimeter in Ohms mode.

3. 3

   Measure the resistance across terminals 2 and 3 of the connector of the O2 sensor itself. This connector has male spade terminals.

4. 4

   Your multimeter should register 2.3 - 4.3 Ohms. If the heater element is fried, your multimeter will show an open circuit usually indicated by the letters OL or a number over 10,000 Ohm's.

Let's examine your test results:

CASE 1: The heater element's resistance is within specification. This is the correct test result and confirms that the heater element, on your 2002-2003 2.5L Nissan Altima, is OK.

CASE 2: The heater element's resistance is NOT within specification. With this test result you can conclude that the heater element within the front O2 sensor is defective. Replacing the front O2 sensor with a new one will solve the front O2 sensor trouble code is lighting up the check engine light on your 2002-2003 2.5L Nissan Altima.

Heated Oxygen Sensor 1 Circuit Diagram

NOTE: The front oxygen sensor wiring diagram above only applies to the 2002-2003 2.5L Nissan Altima.

More 2.5L Nissan Tutorials

To see all of the 2.5L Nissan specific articles, go to: Nissan 2.5L Index Of Articles.

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

• Coil-On-Plug (COP) Coil Test 2.5L Nissan Altima, Sentra (2002-2006).
• How To Test Engine Compression (2.5L Nissan Altima, Sentra).
• How To Test The Fuel Injectors (2.5L Nissan Altima, Sentra).
• How To Test The Alternator (2002-2006 2.5L Nissan Altima).