2001 Chevrolet Blazer DTC P0410 P0135 P0155: How to Clear OBD-II Codes and Pass Inspection
My 2001 Chevrolet Blazer has persistent OBD-II diagnostic trouble codes: P0410, P0135, and P0155. I initially suspected a faulty A.I.R. pump, which was replaced along with the fuses. The vehicle's oxygen sensors are functioning properly, and no active faults were detected during testing—only these codes appear in the history memory. After multiple driving cycles (over 400 miles), the check engine light remains off, but the inspection is still blocked due to unresolved codes. I've followed recommended drive sequences, but the codes persist. The dealership stated that P0135 and P0155 are non-critical for inspection, yet they must clear before a valid inspection can be completed. I'm wondering if the repair shop should have cleared the history codes after replacing the A.I.R. pump to verify whether the issue returns. Additionally, I need guidance on properly executing the drive cycle: what constitutes a cold start (in a 20°F NY climate), how long to hold at half and three-quarter throttle, and whether a scan tool is required to ensure all tests complete successfully.
Are there only history codes with no active DTCs? If so, the issue may not be critical. The PCM will turn off the MIL (Malfunction Indicator Lamp) after three consecutive successful ignition cycles during a diagnostic run that completes without failure. A history code clears after 40 consecutive warm-up cycles if no emission-related diagnostics fail. To clear these codes properly, use an OBD-II scan tool to manually erase them—this ensures accurate results and avoids relying on passive clearing. Always verify the test sequence is fully executed; incomplete tests may prevent code clearance. Reference: https://www.obd-codes.com/trouble_codes/p0410-p0135-p0155-cycle.php