Oxygen Sensor Heater Test -P0135 (1999-2000 2.5L Grand Vitara)

Troubleshooting a diagnostic trouble code (DTC) P0135: Heated Oxygen Sensor Circuit Malfunction Bank 1 Sensor 1 on your 2.5L Suzuki Grand Vitara is a pretty easy affair.

You don't need any expensive diagnostic test equipment... all you'll need is a multimeter. I'll show you the 3 basic tests you'll need to perform to find out.

NOTE: This oxygen sensor is known by several different names:

  1. Upstream Heated Oxygen (O2) Sensor 1.
  2. HO2S Sensor 1.
  3. Oxygen Sensor Bank 1 Sensor 1.
  4. Front Left Oxygen Sensor.

Here are the contents of this tutorial:

  1. Circuit Descriptions of Bank 1 Sensor 1 Oxygen Sensor.
  2. TEST 1: Verifying the Heater Element is Getting Power.
  3. TEST 2: Verifying the Heater Element is Getting Ground.
  4. TEST 3: Testing the Heater Element's Resistance.
  5. Oxygen Sensor Locations (1999-2000 2.5L Grand Vitara ).
  6. Where to Buy the Oxygen Sensor and Save Some $$$.
  7. More 2.5L Suzuki Diagnostic Tutorials.

NOTE: To test a P0155: Heated Oxygen Sensor Circuit Malfunction Bank 2 Sensor 1 trouble code, take a look at this tutorial: Oxygen Sensor Heater Test -P0155 (2.5L Grand Vitara).

Circuit Descriptions of
Bank 1 Sensor 1 Oxygen Sensor

Oxygen Sensor Heater Test -P0135 (1999-2000 2.5L Grand Vitara)

Your 1999-2000 2.5L Suzuki Grand Vitara has a total of 4 oxygen sensors. The O2 sensor that we're gonna' test is the one that's identified as the Bank 1 Sensor 1 O2 sensor. This sensor is usually abbreviated as HO2S11 and if you're wondering where exactly it's located... take a look at this section: 1999-2000 2.5L Grand Vitara Oxygen Sensor Locations.

All 4 oxygen sensors, on your 2.5L Suzuki Grand Vitara, are a 4 wire sensor. This is due to the fact that two of those wires feed power and ground to an internal heater.

The other two wires are the ones that connect to the oxygen content monitoring (of the exhaust gas) part of the downstream O2 sensor.

Below, you'll find the color of the wires of the engine wiring harness oxygen sensor connector for the left front oxygen sensor (HO2S 11):

Bank 1 Sensor 1 Oxygen Sensor Pinout
(1999-2000 2.5L Grand Vitara)
Pin Wire Color Description
1 GRY/YEL O2 Signal Ground
2 RED O2 Signal
3 GRY Heater Ground (-)
4 BLU Heater Power (+)

TEST 1: Verifying the Heater Element is Getting Power

Oxygen Sensor Heater Test -P0135 (1999-2000 2.5L Grand Vitara)

The first thing we're gonna' do is to make sure that the front left O2 sensor (HO2S 11) is getting power.

We're gonna' check for this power on the blue (BLU) wire of the O2 sensor engine wiring harness connector. This power is in the form of 12 Volts DC.

To see if this voltage is present (or not), we'll do a simple multimeter voltage test.

CAUTION: The exhaust system and the oxygen sensors get and stay very hot even after the engine is off! Perform this test with a completely cold engine. Be careful and take all necessary safety precautions! If you raise your vehicle with a jack, place it on jack stands!

IMPORTANT: The pinout in the illustration above is of the connector on the oxygen sensor itself. To check for power, you need to test the BLU wire of the engine wiring harness sensor connector.

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

  1. 1

    Locate the front left oxygen sensor (HO2S 11) and disconnect it from its engine wiring harness connector.

  2. 2

    Locate the BLU wire of the engine wiring harness oxygen sensor connector.

  3. 3

    With your multimeter in Volts DC mode, probe the BLU with the red multimeter lead.

    Ground the black multimeter lead directly on the battery's negative terminal. (if you don't have a multimeter or need to upgrade your's take a look at my recommendation here: Buying a Digital Multimeter for Automotive Diagnostic Testing).

  4. 4

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

Let's take a look at your test results:

CASE 1: Your multimeter shows that the BLU wire is feeding 10 to 12 Volts DC to HO2S 11- Good, since this confirms that the oxygen sensor's heater element is getting power.

The next step is to make check that the black (GRY) wire, of the O2 sensor engine wiring 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 shows that the BLU wire IS NOT feeding 10 to 12 Volts DC to HO2S 11- 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 left front oxygen sensor (HO2S 11) itself IS NOT BAD... since without power, the heater element within it 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 using a wiring diagram.