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P0420 Diagnostic Trouble Code Discussion for April 2011

Catalyst Efficiency Below Normal (Bank 1)


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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1997 BMW 318i 1.9L MIL Lamp on VIN: WBACC9328V
P0420: Cat efficency. ... this car for the past 2 years I will give a quick summary I have put in 4 after market cats every time the check engine light would come on the only code stored was the P0420 and all the cats would break apart. I replaced the thermostat and did plugs and w...
April 04, 2011
2004 Chevrolet Silverado 2500 HD 6.0L Misfire VIN: 1GCHK29U24
P0420: Catalyst System Low Efficiency (Bank 1). Hi guys. I have a 2004 Chevy Silverado 2500HD. Has misfires on all cylinders. Customer replaced plugs and wires with new sets, hoping to cure the problem. We have done a crank relearn, which did not help. We replaced the crankshaft sensor, still no change. We ...
April 21, 2011
2000 Mazda Protege ES 1.8L Hesitation VIN: JM1BJ2215Y
P0420: Catalyst Efficiency Below Normal (Bank 1). Hi everyone. This mazda came in with loss power under acceleration. I clear the check engine light. Code never come back. It's feel like transmission not upshift or restrict converter. I remove the front o2 sensor and look inside the cats,it's not melt, with t...
April 26, 2011
2000 Mazda Protege ES 1.8L Hesitation VIN: JM1BJ2215Y
P0420: Catalyst Efficiency Below Normal (Bank 1). Hi everyone. This mazda came in with loss power under acceleration. I clear the check engine light. Code never come back. It's feel like transmission not upshift or restrict converter. I remove the front o2 sensor and look inside the cats,it's not melt, with t...
April 27, 2011
2003 Honda Accord LX 2.4L Misfire, MIL Lamp on VIN: 3HGCM56303
P0420: Catalyst Efficiency Below Threshold (Bank 1). Dead miss on #1. Replaced plug, no change. Coil fires to ground. Swapped #1, #2 coils, miss did not follow coil. Compression 175 on #1 and #2. Observed piston movement #1. Noid light flashes for #1. Removed fuel rail and cranked engine, all injectors spray equ...
April 29, 2011
1997 BMW 318i 1.9L MIL Lamp on VIN: WBACC9328V
P0420: Cat efficency. ... this car for the past 2 years I will give a quick summary I have put in 4 after market cats every time the check engine light would come on the only code stored was the P0420 and all the cats would break apart. I replaced the thermostat and did plugs and w...
April 04, 2011
2004 Chevrolet Silverado 2500 HD 6.0L Misfire VIN: 1GCHK29U24
P0420: Catalyst System Low Efficiency (Bank 1). Hi guys. I have a 2004 Chevy Silverado 2500HD. Has misfires on all cylinders. Customer replaced plugs and wires with new sets, hoping to cure the problem. We have done a crank relearn, which did not help. We replaced the crankshaft sensor, still no change. We ...
April 21, 2011
2000 Mazda Protege ES 1.8L Hesitation VIN: JM1BJ2215Y
P0420: Catalyst Efficiency Below Normal (Bank 1). Hi everyone. This mazda came in with loss power under acceleration. I clear the check engine light. Code never come back. It's feel like transmission not upshift or restrict converter. I remove the front o2 sensor and look inside the cats,it's not melt, with t...
April 26, 2011
2000 Mazda Protege ES 1.8L Hesitation VIN: JM1BJ2215Y
P0420: Catalyst Efficiency Below Normal (Bank 1). Hi everyone. This mazda came in with loss power under acceleration. I clear the check engine light. Code never come back. It's feel like transmission not upshift or restrict converter. I remove the front o2 sensor and look inside the cats,it's not melt, with t...
April 27, 2011
2003 Honda Accord LX 2.4L Misfire, MIL Lamp on VIN: 3HGCM56303
P0420: Catalyst Efficiency Below Threshold (Bank 1). Dead miss on #1. Replaced plug, no change. Coil fires to ground. Swapped #1, #2 coils, miss did not follow coil. Compression 175 on #1 and #2. Observed piston movement #1. Noid light flashes for #1. Removed fuel rail and cranked engine, all injectors spray equ...
April 29, 2011