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P0420 Diagnostic Trouble Code Discussion for October 2008

Catalyst Efficiency Below Normal (Bank 1)


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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1999 Chevrolet K1500 Suburban 5.7L Excessive Emissions, Poor Idle Quality VIN: 3GNFK16R2X
P0420: Catalyst System Low Efficiency (Bank 1). THANKS IN ADVANCE this suburban idles rough - not really rough but every 3 months or so it will throw a po300. this time the misfire monitors were hi on 7, 3, and 4. 1234-2344 misfires. Freeze Frame is recorded at idle. i can drive this thing down the road and...
October 03, 2008
1997 Chevrolet Blazer 4.3L Excessive Emissions VIN: 1GNCT18WOV
P0420: Catalyst System Low Efficiency (Bank 1). ... had fallen apart internally, also changed fuel injectors due to excessive negative fuel trims of -13.0% on both banks, after injectors and cat were replaced fuel trims were -3.0% both banks, let customer take vehicle. vehicle came back about 1500 miles lat...
October 06, 2008
1997 Jeep Grand Cherokee Limited 5.2L Hesitation, Poor Fuel Economy, spar k knock VIN: 1J4GZ78Y7V
P0420: Catalyst Efficiency Below Normal (Bank 1). After i had all new exhaust installed, along with both new o2 sensors installed, the convertor code came back,along with spark knock on accel. So i did a full tune up. Plugs,wires,cap,rotor, o.e.pvc valve and fuel filter. I also check for vac leaks,fixed a cou...
October 08, 2008
1997 Jeep Grand Cherokee Limited 5.2L Hesitation, Poor Fuel Economy, spar k knock VIN: 1J4GZ78Y7V
P0420: Catalyst Efficiency Below Normal (Bank 1). After i had all new exhaust installed, along with both new o2 sensors installed, the convertor code came back,along with spark knock on accel. So i did a full tune up. Plugs,wires,cap,rotor, o.e.pvc valve and fuel filter. I also check for vac leaks,fixed a cou...
October 09, 2008
1997 Chevrolet Blazer 4.3L Excessive Emissions VIN: 1GNCT18WOV
P0420: Catalyst System Low Efficiency (Bank 1). ... had fallen apart internally, also changed fuel injectors due to excessive negative fuel trims of -13.0% on both banks, after injectors and cat were replaced fuel trims were -3.0% both banks, let customer take vehicle. vehicle came back about 1500 miles lat...
October 10, 2008
2001 Chevrolet Prizm 1.8L MIL Lamp on VIN: 1Y1SK52871
P0420: Catalyst Effiency below threshold. ... Chevrolet Prism. replaced catalytic converter 2/07 due to P0420 & after temp test converter was not working. now customer has returned with check engine light on again, and low and behold, code P0420 has returned. temp tested converter and outlet was 2...
October 15, 2008
2002 Buick Regal LS 3.8L MIL Lamp on VIN: 2G4WB55K62
P0420: Catalyst System Low Efficiency (Bank 1). Replaced converter with OE (twice) and code returns. No other codes. O2 readings appear normal. I assume converter isn't the problem. What should I look for?
October 16, 2008
2005 Dodge Durango Limited 5.7L MIL Lamp on VIN: 1D8HB58D35
P0420: Catalyst Efficiency Below Normal (Bank 1). ... in with P0420, poor cat efficiency. Both upstreem O2's looked lazy so I replaced them. They looked a little better after, customer picked it up and was gone for about a week. Came back in today with the same code. I checked everything mentioned in test res...
October 16, 2008
2005 Dodge Durango Limited 5.7L MIL Lamp on VIN: 1D8HB58D35
P0420: Catalyst Efficiency Below Normal (Bank 1). ... in with P0420, poor cat efficiency. Both upstreem O2's looked lazy so I replaced them. They looked a little better after, customer picked it up and was gone for about a week. Came back in today with the same code. I checked everything mentioned in test res...
October 17, 2008
2001 Audi A6 Quattro 2.8L MIL Lamp on VIN: WAUEH54BX1
P0420: Cat System Efficiency Below Threshold Bank 1. First saw this vehicle a year ago for a bad cat (rattles inside). Replaced it along with O2. Few months later we got a code referring to the other cat, so we replaced it, along with the O2. Three months later the MIL is on with codes referring to both cats eff...
October 20, 2008
2000 Pontiac Sunfire GT 2.4L Surge, MIL Lamp on VIN: 3G2JD12T3Y
P0420: Catalyst System Low Efficiency. ... a ses light on, stored code p0420 - cat efficiency failed. Freeze frame showed it happend at idle. The o2 sensors are good. The cat was replaced 4000 kms ago. The car does not idle smooth, surges slightly. Vacuum is steady, tune-up condition is good. I che...
October 20, 2008
2001 Volkswagen Golf GL 2.0L runs fine VIN: 9BWBS21J51
P0420: cat. I need some info on the 17772 or p1364 code. I cant find anything in Mitchell on this code. Can anybody help out? The car runs fine and the customer said it always runs good.
October 29, 2008
2002 Chevrolet Impala 3.8L Poor Idle Quality, Cuts out, MIL Lamp on
P0420: Catalyst System Low Efficiency. Customer came in for yearly state inspection, which in Upstate New York you have to pass both a safety and a low enhanced emissions test. Check engine light was on so we scanned car and found po420 catalyst eff. limit. Car has a new convertor on it. And new o2...
October 30, 2008
1999 Chevrolet K1500 Suburban 5.7L Excessive Emissions, Poor Idle Quality VIN: 3GNFK16R2X
P0420: Catalyst System Low Efficiency (Bank 1). THANKS IN ADVANCE this suburban idles rough - not really rough but every 3 months or so it will throw a po300. this time the misfire monitors were hi on 7, 3, and 4. 1234-2344 misfires. Freeze Frame is recorded at idle. i can drive this thing down the road and...
October 03, 2008
1997 Chevrolet Blazer 4.3L Excessive Emissions VIN: 1GNCT18WOV
P0420: Catalyst System Low Efficiency (Bank 1). ... had fallen apart internally, also changed fuel injectors due to excessive negative fuel trims of -13.0% on both banks, after injectors and cat were replaced fuel trims were -3.0% both banks, let customer take vehicle. vehicle came back about 1500 miles lat...
October 06, 2008
1997 Jeep Grand Cherokee Limited 5.2L Hesitation, Poor Fuel Economy, spar k knock VIN: 1J4GZ78Y7V
P0420: Catalyst Efficiency Below Normal (Bank 1). After i had all new exhaust installed, along with both new o2 sensors installed, the convertor code came back,along with spark knock on accel. So i did a full tune up. Plugs,wires,cap,rotor, o.e.pvc valve and fuel filter. I also check for vac leaks,fixed a cou...
October 08, 2008
1997 Jeep Grand Cherokee Limited 5.2L Hesitation, Poor Fuel Economy, spar k knock VIN: 1J4GZ78Y7V
P0420: Catalyst Efficiency Below Normal (Bank 1). After i had all new exhaust installed, along with both new o2 sensors installed, the convertor code came back,along with spark knock on accel. So i did a full tune up. Plugs,wires,cap,rotor, o.e.pvc valve and fuel filter. I also check for vac leaks,fixed a cou...
October 09, 2008
1997 Chevrolet Blazer 4.3L Excessive Emissions VIN: 1GNCT18WOV
P0420: Catalyst System Low Efficiency (Bank 1). ... had fallen apart internally, also changed fuel injectors due to excessive negative fuel trims of -13.0% on both banks, after injectors and cat were replaced fuel trims were -3.0% both banks, let customer take vehicle. vehicle came back about 1500 miles lat...
October 10, 2008
2001 Chevrolet Prizm 1.8L MIL Lamp on VIN: 1Y1SK52871
P0420: Catalyst Effiency below threshold. ... Chevrolet Prism. replaced catalytic converter 2/07 due to P0420 & after temp test converter was not working. now customer has returned with check engine light on again, and low and behold, code P0420 has returned. temp tested converter and outlet was 2...
October 15, 2008
2002 Buick Regal LS 3.8L MIL Lamp on VIN: 2G4WB55K62
P0420: Catalyst System Low Efficiency (Bank 1). Replaced converter with OE (twice) and code returns. No other codes. O2 readings appear normal. I assume converter isn't the problem. What should I look for?
October 16, 2008
2005 Dodge Durango Limited 5.7L MIL Lamp on VIN: 1D8HB58D35
P0420: Catalyst Efficiency Below Normal (Bank 1). ... in with P0420, poor cat efficiency. Both upstreem O2's looked lazy so I replaced them. They looked a little better after, customer picked it up and was gone for about a week. Came back in today with the same code. I checked everything mentioned in test res...
October 16, 2008
2005 Dodge Durango Limited 5.7L MIL Lamp on VIN: 1D8HB58D35
P0420: Catalyst Efficiency Below Normal (Bank 1). ... in with P0420, poor cat efficiency. Both upstreem O2's looked lazy so I replaced them. They looked a little better after, customer picked it up and was gone for about a week. Came back in today with the same code. I checked everything mentioned in test res...
October 17, 2008
2001 Audi A6 Quattro 2.8L MIL Lamp on VIN: WAUEH54BX1
P0420: Cat System Efficiency Below Threshold Bank 1. First saw this vehicle a year ago for a bad cat (rattles inside). Replaced it along with O2. Few months later we got a code referring to the other cat, so we replaced it, along with the O2. Three months later the MIL is on with codes referring to both cats eff...
October 20, 2008
2000 Pontiac Sunfire GT 2.4L Surge, MIL Lamp on VIN: 3G2JD12T3Y
P0420: Catalyst System Low Efficiency. ... a ses light on, stored code p0420 - cat efficiency failed. Freeze frame showed it happend at idle. The o2 sensors are good. The cat was replaced 4000 kms ago. The car does not idle smooth, surges slightly. Vacuum is steady, tune-up condition is good. I che...
October 20, 2008
2001 Volkswagen Golf GL 2.0L runs fine VIN: 9BWBS21J51
P0420: cat. I need some info on the 17772 or p1364 code. I cant find anything in Mitchell on this code. Can anybody help out? The car runs fine and the customer said it always runs good.
October 29, 2008
2002 Chevrolet Impala 3.8L Poor Idle Quality, Cuts out, MIL Lamp on
P0420: Catalyst System Low Efficiency. Customer came in for yearly state inspection, which in Upstate New York you have to pass both a safety and a low enhanced emissions test. Check engine light was on so we scanned car and found po420 catalyst eff. limit. Car has a new convertor on it. And new o2...
October 30, 2008