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Old 05-11-2013, 10:59 PM
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HUMTECH HUMTECH is offline
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Location: Canada
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Default Re: Error codes after installing magnaflow cats

DTC P0135 or P0155Step
Action
Value(s)
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Component Views or Powertrain Control Module Connector End Views
1
Did you perform the Diagnostic System Check?Engine Controls?
?
Go to <a id="s02_rev">Step 2
Go to Diagnostic System Check - Engine Controls
2
Important: Whenever the HO2S heaters are commanded ON with a scan tool, they will continue to be pulsed ON once per second until the ignition is turned OFF for 30 seconds.
  1. Turn ON the ignition, with the engine OFF.
  2. Command the HO2S heaters ON with a scan tool.
  3. Wait 15 seconds to allow the HO2S heater current to stabilize.
  4. Observe the affected HO2S heater current parameter with a scan tool.
Is the HO2S heater current parameter within the specified range?
0.25?3.125 A
Go to <a id="s03_rev">Step 3
Go to <a id="s06_rev">Step 6
3
Observe the Freeze Frame/Failure Records for this DTC.
Did the DTC fail with an engine run time of less that 10 seconds?
?
Go to <a id="s04_rev">Step 4
Go to <a id="s05_rev">Step 5
4
  1. Operate the vehicle within the Conditions for Running the Heater Resistance Test.
  2. Start the engine.
Did the DTC fail this ignition?
?
Go to <a id="s06_rev">Step 6
Go to Intermittent Conditions
5
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the Heater Current Test. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
?
Go to <a id="s06_rev">Step 6
Go to Intermittent Conditions
6
Inspect the O2A fuse.
Is the O2A fuse open?
?
Go to <a id="s07_rev">Step 7
Go to <a id="s08_rev">Step 8
7
Test the ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
?
Go to <a id="s22_rev">Step 22
Go to <a id="s10_rev">Step 10
8
  1. Disconnect the affected HO2S.
  2. Turn ON the ignition, with the engine OFF.
  3. Probe the ignition 1 voltage circuit of the HO2S harness connector on the engine harness side with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
?
Go to <a id="s09_rev">Step 9
Go to <a id="s19_rev">Step 19
<a id="td09_rev"><a href="http://gsi.xw.gm.com/newsi/showDoc.do?docSyskey=1250611&cellId=66527&pubObjSy skey=3144813&from=sm&pubCellSyskey=642081&delivery EffectiveDate=May+1%2C+2013#td09">9
Important: The test lamp may blink prior to commanding the heaters ON. This is because the heaters were commanded ON in a previous step. To command the heaters OFF, turn OFF the ignition for 30 seconds.
  1. Connect a test lamp between the ignition 1 voltage circuit of the HO2S harness connector on the engine harness side and the HO2S heater low control circuit of the HO2S harness connector on the engine harness side.
  2. Command the HO2S heaters ON with a scan tool.
Does the test lamp blink once per second?
?
Go to <a id="s11_rev">Step 11
Go to <a id="s12_rev">Step 12
10
Important: Perform the following test on all HO2S' which are supplied voltage by the suspect circuit.

Test the ignition 1 voltage circuit on the sensor side of the HO2S connector for a short to ground. Refer to Circuit Testing in Wiring Systems.
Is any sensor shorted to ground?
?
Go to <a id="s20_rev">Step 20
Go to Intermittent Conditions
11
Measure the resistance of the following circuits with a DMM:
  • HO2S heater low control circuit
  • Ignition 1 voltage circuit
Refer to Circuit Testing in Wiring Systems.
Is the resistance of either circuit more than the specified value?
3 Ω
Go to <a id="s18_rev">Step 18
Go to <a id="s16_rev">Step 16
12
Is the test lamp on steady?
?
Go to <a id="s13_rev">Step 13
Go to <a id="s14_rev">Step 14
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