P0420 Diagnostic Trouble Code Discussion for February 2017
Catalyst Efficiency Below Normal (Bank 1)
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| Help Request | Posted | |
| 2000 Honda Accord SE 2.3L MIL Lamp on VIN: JHMCG6690Y P0420: Catalyst Efficiency Below Threshold (Bank 1). The problem I am having on this Honda is with the upstream O2 sensor. On a lab scope, the sensor signal is fixed at 2.5 volts. If the sensor is disconnected, on the harness side, the signal wire has 2.5 volts (Coming from the PCM, to the sensor). So does the o... |
February 08, 2017 | |
| 2000 Honda Accord SE 2.3L MIL Lamp on VIN: JHMCG6690Y P0420: Catalyst Efficiency Below Threshold (Bank 1). The problem I am having on this Honda is with the upstream O2 sensor. On a lab scope, the sensor signal is fixed at 2.5 volts. If the sensor is disconnected, on the harness side, the signal wire has 2.5 volts (Coming from the PCM, to the sensor). So does the o... |
February 09, 2017 | |
| 2003 Nissan Altima 2.5L Poor Idle Quality, Hesitation, Surge, Stall, Misfire, MIL Lamp on VIN: 1N4AL11D23 P0420: Catalyst Efficiency Below Normal (Bank 1). Customer complains of stall or almost stalling at stoplight. Sometime hard restart. No start once with cold engine. Started with WOT. Idles up on cold start, slows to about 700 rpm, then sometime slows to almost stall and catches to 800-900.I PLACED RESISTERS ... |
February 17, 2017 | |
| 2010 Audi A5 Quattro 2.0L MIL Lamp on VIN: WAULFAFR7A P0420: Cat efficiency below threshold. The car came in with a P0420 and P0456 catalyst and very small evap leak. We did all the normal testing to make sure the cat was bad and then replaced the cat with a DEC part. The light came back on 2 days later. Has anyone had a bad DEC cat? What else could b... |
February 28, 2017 |
