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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 115 (Engine Control System Self Diagnostics - 4-Cylinder) >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank No. 1) >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Toyota Camry Solara. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Read freeze frame data using hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When trouble shooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
  1. Check if there are other codes (besides DTC P0420) being output. If other codes are output, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other codes are output, go to next step.
  2. Check if there is a gas leak on the exhaust system. If the results are OK, go to next step. If the results are not good, repair or replace.
  3. Check the air-fuel ratio (A/F) sensor (bank No. 1 sensor No. 1). See SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If the results are OK, go to next step. If the results are not good, replace A/F sensor. See REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
  4. Check the heated oxygen sensor (bank No. 1 sensor No. 2). See SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If the results are OK, replace the three-way catalytic converter. If the results are not good, replace three-way catalytic converter. See REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
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