Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2003 Acura 3.2TL BaseFACTORY OEM SERVICE PROCEDURE
DTC P0420: Catalyst System Efficiency Below Threshold: 3.2CL
- Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Start engine and run at 3000 RPM, with no load (in park or neutral) until radiator fan comes on.
- Connect scan tool to DLC. Test drive vehicle at 40-55 MPH for about 2 minutes. Decelerate with throttle completely closed for at least 3 seconds. Reduce speed to 35 MPH and try to hold until scan tool indicates FAIL or PASS as Three Way Catalytic Converter (TWC) test result. If test result is FAIL, check TWC and replace if necessary. If test result is PASS, problem is intermittent. System is okay at this time.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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