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.
Diagnostic Procedure
2004 Acura 3.5RLSECTION Diagnostic Procedure
- Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Start engine. Hold engine speed at 3000 RPM with no load and transmission in Park or Neutral until radiator fan comes on. Install SCS Service Connector (07PAZ-0010100) to Service Check Connector. See Figure .
- Test drive vehicle at 40-55 MPH for at least 2 minutes. Decelerate for at least 3 seconds with throttle completely closed. Then, reduce speed to 35 MPH and try to hold speed until readiness code comes on. If DTC P0420 sets, go to next step. If DTC P0420 does not reset, problem is intermittent. System is okay at this time.
- Remove three-way catalytic converter (TWC). Shine a flashlight into catalyst inlet while looking into catalyst outlet. Check for plugging, melting or cracking. Replace TWC if necessary.
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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.