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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 29 (Engine Exhaust System) >> Diagnostic Information and Procedures >> Restricted Exhaust >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. 4:  The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the J 35314-A  Exhaust Back Pressure Gage. See Special Tools .Removing the heated oxygen (HO2S) sensor may set a diagnostic trouble code (DTC). When finishing this diagnostic table, be sure to clear all codes.
  2. 5:  This step will isolate the catalytic converter from the remainder of the exhaust system.
Restricted Exhaust

Step Action Value(s) Yes No
1 Did you verify the customers complaint? - Go to Step 2  -
2 Did you review the exhaust symptoms diagnostic information and perform the necessary inspections? - Go to Step 3  Go to Symptoms - Engine Exhaust 
3 Is the system equipped with dual exhaust? - Go to Diagnostic Aids Go to Step 4 
4 
  1. Remove the pre-catalyst HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .
  2. Install the J 35314-A  Exhaust Back Pressure Gage in place of the HO2S sensor. See Special Tools .
  3. Start the engine.
  4. Increase and monitor the engine speed at, 2500 RPM.
  5. Observe the exhaust system back pressure reading on the gage.
Does the reading exceed the specified value?		 9 kPa (1.25 psi) Go to Step 5  Go to Step 8 
5 
  1. Turn the engine off and place the ignition in the lock position.
  2. Remove the J 35314-A  . See Special Tools .
  3. Re-install the pre-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .
  4. Remove the post-catalyst HO2S sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 .
  5. Install the J 35314-A  in place of the post-catalyst HO2S sensor. See Special Tools .
  6. Start the engine.
  7. Increase and monitor the engine speed at 2500 RPM.
  8. Observe the exhaust system back pressure reading on the gage.
Does the reading exceed the specified value?		 9 kPa (1.25 psi) Go to Step 6  Go to Step 7 
6 Inspect the exhaust system for the following conditions:
  • Damage in the exhaust pipe
  • Debris in the exhaust pipe
  • Muffler or resonator, if equipped, internal failure
  • Two-layer exhaust pipe separation

Did you find and correct the condition?		 - Go to Step 8  -
7 Replace the exhaust system. Refer to Exhaust System Replacement .
Did you find and correct the condition?		 - Go to Step 8  -
8
  1. Remove the J 35314-A  . See Special Tools .
  2. Reinstall the applicable HO2S sensor. Refer to one of the following:
  3. Clear any codes.
  4. Road test the vehicle in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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