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Home >> Isuzu >> 2004 >> Axiom Base, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine DRIVEABILITY And Emissions - DTC P0101 To P0174 >> DTC P0155: O2 Sensor Heater Circuit (Bank 2 Sensor 1) >> Test Description
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Test Description

Number(s) below refer to the step number(s) on the Diagnostic Chart.

  1. 2. The HO2S should be allowed to cool before performing this test. If the HO2S heater is functioning, the signal voltage will gradually increase or decrease as the sensor element warms. If the heater is not functioning, the HO2S signal will remain near the 470 mV bias voltage.
  2. 4. Ensures that the ignition feed circuit to the HO2S is not open or shorted. The test light should be connected to a good chassis ground, in case the HO2S low or HO2S heater ground circuit is faulty.
  3. 5. Checks the HO2S heater ground circuit.
  4. 6. Checks for an open or shorted HO2S heater element.
  5. 10. An open HO2S signal or low circuit can cause the HO2S heater to appear faulty. Check these circuits before replacing the sensor.
DTC P0155 - O2 SENSOR HEATER CIRCUIT (BANK 2 SENSOR 1)

Step Action Values Yes No
1 Was the "On-Board Diagnostic (OBD-II) System Check" performed? - Go to Step 2 Go to On-Board Diagnostic (OBD-II) System Check
1
  1. Install Tech 2.
  2. Engine Start.
  3. Monitor B2 HO2S1 Heater Current value.
Is B2 HO2S1 Heater current value is below the specified value?		 0.1A Go to Step 3 Refer to DIAGNOSTIC AIDS 
3 Inspect the fuse for the Bank 2 HO2S1 ignition feed.
Is the fuse open?		 - Go to Step 15 Go to Step 4
4
  1. Ignition "OFF".
  2. Raise the vehicle.
  3. Disconnect the Bank 2 HO2S1 electrical connector.
  4. Using a test light connected to a known good ground (do not use Bank 2 HO2S1 heater ground or Bank 2 HO2S1 low), probe the ignition feed circuit at the Bank 2 HO2S1 electrical connector (ECM harness side).
Does the test light illuminate?		 - Go to Step 5 Go to Step 7
5 Connect the test light between Bank 2 HO2S1 ignition feed and Bank 2 HO2S1 heater ground.
Does the test light illuminate?		 - Go to Step 6 Go to Step 8
6
  1. Allow the HO2S to cool for at least 15 minutes.
  2. Using a DVM, measure resistance between the Bank 2 HO2S1 ignition feed and the Bank 2 HO2S1 heater ground at the Bank 2 HO2S1 pigtail.
Is the HO2S resistance within the specified values?		 3--6 Ω Go to Step 9 Go to Step 10
7 Repair the open Bank 2 HO2S1 ignition feed circuit to Bank 2 HO2S 1.
Is the action complete?		 - Verify repair -
8 Repair the open Bank 2 HO2S1 heater ground circuit.
Is the action complete?		 - Verify repair -
9
  1. Check for a poor connection at the Bank 2 HO2S1 harness terminals.
  2. If a poor connection is found, replace terminals.
Was a poor connection found?		 - Verify repair Go to Step 10
10 Check for a poor Bank 2 HO2S1 signal or low circuit terminal connection at the Bank 2 HO2S1 harness connector and replace terminal(s) if necessary.
Did any terminals require replacement?		 - Verify repair Go to Step 11
11
  1. Ignition "OFF".
  2. Disconnect the ECM and check the continuity of the Bank 2 HO2S1 signal circuit and the Bank 2 HO2S1 low circuit.
  3. If the Bank 2 HO2S1 signal circuit or HO2S low circuit measures over 5 ohms, repair open or poor connection as necessary.
Was a problem found?		 - Verify repair Go to Step 12
12 Check for a poor Bank 2 HO2S1 low circuit terminal connection at the ECM and replace the terminal if necessary.
Did the terminal require replacement?		 - Verify repair Go to Step 13
13 Check for a poor Bank 2 HO2S1 signal circuit terminal connection at the ECM and replace the terminal if necessary.
Did the terminal require replacement?		 - Verify repair Go to Step 14
14 Replace Bank 2 HO2S 1.
Is the action complete?		 - Verify repair -
15 Locate and repair short to ground in Bank 2 HO2S1 ignition feed circuit and replace the faulty fuse.
Is the action complete?		 - Verify repair -
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