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P0420 Diagnostic Trouble Code Discussion for May 2013

Catalyst Efficiency Below Normal (Bank 1)


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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2002 Pontiac Grand Prix SE 3.1L Excessive Emissions, Misfire, MIL Lamp on VIN: 1G2WK52J32
P0420: Catalyst System Low Efficiency. Came in with a p0420. Replaced cat, came back aprox 500 mi later with same code, replace cat again with a OE unit, and new front and rear O2's. Back again with p0420 and p0300 after aprox 50 mi. Cyl #4 has a very slight miss, cant feel it but the verus is show...
May 07, 2013
2009 Chevrolet Malibu LS 2.4L Hesitation, Poor Fuel Economy, MIL Lamp on VIN: 1G1ZG57B79
P0420: catalist efficency low. replaced both actuators cleared codes and test drove. symptoms persist but no codes returned within 12 drive cycles. checked cat for blockage all seemed ok. please help!!! this thing is throwing me for a loop and the customer is from out of town in our waiting...
May 13, 2013
2003 Subaru Forester X 2.5L Hesitation, Surge VIN: JF1SG636S3
P0420: Catalyst Efficiency Below Normal (Bank 1). ... after 30 miles of driving. Had a P0420 for catalyst efficiency. Customer also complained that he was towing his boat and the further he towed it, the loss of power was greater and greater. So we replaced the converters. No...
May 17, 2013
2003 Chevrolet Monte Carlo LS 3.4L Poor Idle Quality, Hesitation VIN: 2G1WW12E43
P0420: Catalyst System Low Efficiency. This vehicle came in with a hesitation complaint. We noticed a collapsed vacuum line on the evap solenoid and that the ect was unplugged which account for the ect code. This vehicle will run great then all of a sudden the fuel trims go to -20 and it starts sur...
May 22, 2013
2003 Chevrolet Monte Carlo LS 3.4L Poor Idle Quality, Hesitation VIN: 2G1WW12E43
P0420: Catalyst System Low Efficiency. This vehicle came in with a hesitation complaint. We noticed a collapsed vacuum line on the evap solenoid and that the ect was unplugged which account for the ect code. This vehicle will run great then all of a sudden the fuel trims go to -20 and it starts sur...
May 23, 2013
2002 Pontiac Grand Prix SE 3.1L Excessive Emissions, Misfire, MIL Lamp on VIN: 1G2WK52J32
P0420: Catalyst System Bank 1 Low Efficiency. Came in with a p0420. Replaced cat, came back aprox 500 mi later with same code, replace cat again with a OE unit, and new front and rear O2's. Back again with p0420 and p0300 after aprox 50 mi. Cyl #4 has a very slight miss, cant feel it but the verus is show...
May 07, 2013
2009 Chevrolet Malibu LS 2.4L Hesitation, Poor Fuel Economy, MIL Lamp on VIN: 1G1ZG57B79
P0420: catalist efficency low. replaced both actuators cleared codes and test drove. symptoms persist but no codes returned within 12 drive cycles. checked cat for blockage all seemed ok. please help!!! this thing is throwing me for a loop and the customer is from out of town in our waiting...
May 13, 2013
2003 Subaru Forester X 2.5L Hesitation, Surge VIN: JF1SG636S3
P0420: Catalyst Efficiency Below Normal (Bank 1). ... of a hesitation/surge at cruise after 30 miles of driving. Had a P0420 for catalyst efficiency. Customer also complained that he was towing his boat and the further he towed it, the loss of power was greater and greater. So we replaced the converters. No...
May 17, 2013
2003 Chevrolet Monte Carlo LS 3.4L Poor Idle Quality, Hesitation VIN: 2G1WW12E43
P0420: Catalyst System Low Efficiency. This vehicle came in with a hesitation complaint. We noticed a collapsed vacuum line on the evap solenoid and that the ect was unplugged which account for the ect code. This vehicle will run great then all of a sudden the fuel trims go to -20 and it starts sur...
May 22, 2013
2003 Chevrolet Monte Carlo LS 3.4L Poor Idle Quality, Hesitation VIN: 2G1WW12E43
P0420: Catalyst System Low Efficiency. This vehicle came in with a hesitation complaint. We noticed a collapsed vacuum line on the evap solenoid and that the ect was unplugged which account for the ect code. This vehicle will run great then all of a sudden the fuel trims go to -20 and it starts sur...
May 23, 2013