Hey guys,Steve from Austin,Ky here.Just bought a 2003 Protégé 5 with 173,000 miles on it.2.0L engine with 5 speed manual.I'm getting the PO421 code,bad catalytic converter(1st one right off engine).Do I really need to replace this?I have seen racing headers for this engine that have nowhere for a cat,just four pipes into one that join to rest of exhaust.It will cost 4-500 to replace cat,or 2-300 for headers.If I put on headers what other changes will I have to make(there is an O2 sensor at the current cat).Will there be reprogramming of computer?Drilling to replace O2 sensor? Or do I just run a straight pipe? I'd appreciate any information,this is my first 4 cyl front wheel drive car and it is very foreign to me.Thanks for all your help.
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New member question:Replace front catalytic converter with straight pipe?
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If you run a header with no front cat, it's probably illegal, as it is in most places. If you want to do it, you can run an O2 sensor spacer on the secondary O2. This sensor is for cat diagnosis only. You can also put the spacer on your current secondary O2. I officially don't endorse this, just offering up the info. There's fines in most places if you get caught tampering with emissions.
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The front O2 sensor maintains the stoichiometric A/F mixture in closed loop operation. You need it for proper operation and to minimize emissions.
Happy Motoring!02 DX Millenium Red - The Penultimate Driving Machine
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If you do decide to stick with a cat, free-flow types are available from Magnaflow.
Check out: http://www.wihandyman.com/forum/showthread.php?57477
Happy Motoring!02 DX Millenium Red - The Penultimate Driving Machine
MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
MP3 Shifter, Knob and Aluminum Pedal Set
Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter
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Originally posted by goldstar View PostIf you do decide to stick with a cat, free-flow types are available from Magnaflow.
Check out: http://www.wihandyman.com/forum/showthread.php?57477
Happy Motoring!
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Well, we'll see. It's been one year now and still going strong.
Happy Motoring!02 DX Millenium Red - The Penultimate Driving Machine
MP3 Strut Tower Bar kit; Cusco Front Lower Arm Tie Bar
MSP Springs, Struts, Stabilizer Bars, Trailing Links, #3 Engine Mount
Kartboy Stabilizer Bar Bushings; Nyloil Shifter Bushings; Red Line MT-90 Gear Oil
MP3 Shifter, Knob and Aluminum Pedal Set
Suvlights HD Wiring Harness; Osram Night Breaker H4 Bulbs; Exide Edge AGM Battery
Summer: 5Zigen FN01R-C 16 x 7" Wheels; Yoko S.drive 205/45-16s
Winter: Enkei OR52 16 x 7" Wheels; Falken Ziex ZE-912 205/45-16s
Modified OEM Air Intake; Racing Beat Exhaust System; Techna-Fit SS Clutch Line
Denso SKJ16CR-L11 Extended Tip Spark Plugs; Magnecor Wires
Power Slot Front Brake Rotors; Techna-Fit SS Brake Lines; Hawk HPS Pads
Red Line Synthetic Engine Oil; C/S Aluminum Oil Cap
Cyberdyne Digital Gauges: Tach; Ambient Air Temp; Voltmeter
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