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.
2002 Chevrolet Impala Base, 3.4 EFACTORY OEM SERVICE PROCEDURE
Inspection/Maintenance System DTCS: Description
The following DTCs are required to set system status to YES:
Catalyst System
- P0420 - Catalyst System Low Efficiency
EGR System
- P0401- EGR Flow Insufficient
- P0404 - EGR Open Position Performance
- P0405 - EGR Position Sensor Circuit - Low Voltage
- P1404 - EGR Closed Position Performance
EVAP System
- P0440 - EVAP System
- P0442 - EVAP System Small Leak Detected
- P0446 - EVAP Vent System Performance
- P0447 - EVAP Vent Valve Control Circuit - Low Voltage
- P1441 - EVAP System Flow During Non-Purge
Oxygen Sensor System
- P0133 - HO2S/O2S Slow Response (Sensor 1)
- P0140 - HO2S Circuit Insufficient Activity (Sensor 2)
- P1133 - HO2S Insufficient Switching (Sensor 1)
- P1134 - HO2S Transition Time Ratio (Sensor 1)
Oxygen Sensor Heater System
- P0135 - HO2S Heater Performance (Sensor 1)
- P0141 - HO2S Heater Performance (Sensor 2)
Diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.