n2oTransAmLT1

I took my beast out for an autotap log today and dont you know it threw a check engine code. The code is:
P0420 TWC System Low Efficiency Bank 1. What does this mean? What do I need to fix or replace? And, could this be the cause of my detonation problems? Thanks

CR97WS6

In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), a three-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and carbon monoxide. The catalyst also reduces NOx, converting it to nitrogen. The PCM has the capability to monitor this process using Bank 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1. If a problem exists which causes the PCM to detect excessive Bank 1 HO2S #2 activity outside of an acceptable range for an extended period of time, the PCM will set DTC P0420. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.

Conditions for Setting the DTC

No MAF, MAP, ECT, Left Bank HO2S, Misfire, Left Bank Fuel Trim, Injector, VSS, IAC, Engine coolant fan(s), Transmission DTCs set.
Engine operating.
Engine coolant temperature greater than 51°C (124°F).
Vehicle speed is between 32 km/h (20 mph) and 121 km/h (75 mph).
Throttle angle greater than 2%.
Engine speed less than 3500 RPM.
MAP between 25 kPa and 80 kPa.
Air flow is between 15 gm/s and 100 gm/s.
Closed loop fuel control enabled.
The PCM determines oxygen storage capability of the catalytic converter has degraded below a calibrated threshold.
Action Taken When the DTC Sets
The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.
The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated.

Conditions for Clearing the MIL/DTC

The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
PCM battery voltage is interrupted.
Using a Scan tool.

Basically, check your cat to see if its bad, then check your o2 sensor. probably bad cat.

hope this helps!

DubbyZ28Camaro

You took that off of service.gm.com didn't you???

I wondered why that sounded so damn smart...

Injuneer

To reduce it to simple terms, either:

-the cat on the drivers side is dead
-the after-cat O2 sensor on the drivers side is dead, the wire is loose or burned, or the heater circuit is not working.

CR97WS6

Maybe......Maybe not!

blkn'silver94

would this be the same on a 2001 SS?...my buddy's just set that code off yesterday after having a cutout added about 2 months ago. The guys at the dealership said it was be cause of the cutout..and just cleared the code and let him take it back, no work was done..what really happened? ...i've never heard of anyone getting codes because of a cutout?..thanks Tony