LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 111 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0135: Ho2S1 Heater Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition OFF. If engine has been operating, allow engine to cool for about 30 minutes to ensure HO2S1 has cooled down. Turn ignition ON, engine OFF. Using scan tool, command HO2S1 on for one minute. If reading gradually changes towards zero volts, problem is intermittent. See DIAGNOSTIC AIDS  . If reading does not gradually change towards zero volts, go to next step.
  2. Check EMISS fuse (10-amp) in underhood fuse block. Replace fuse and retest if open. If fuse continues to open, check for a short to ground in White wire between underhood fuse block and HO2S1 or for shorted HO2S1 heater. Swap main relay with a known good relay. Power to EMISS fuse is supplied through main relay. Disconnect HO2S1. Turn ignition ON, engine OFF. Connect a test light between HO2S1 connector terminal "D" (White wire) and ground. If test light is on, go to next step. If test light is off, repair open in White wire between underhood fuse block and HO2S1.
  3. Turn ignition OFF. Disconnect ECM connector J2. Using a DVOM, measure resistance of Dark Green wire between ECM and HO2S1. If resistance is less than 2 ohms, go to next step. If resistance is not less than 2 ohms, repair open in Dark Green wire.
  4. Using a DVOM, measure resistance of HO2S1 heater. If resistance is 10-15 ohms, check terminals. If terminals are okay, replace ECM. If resistance is not 10-15 ohms, replace HO2S1.
scientia non olet · About LEMON Manuals