P0420 and P0430

wow no year car told. now that is a Hard row to hoe.. 2007 to NOW.
no engine told and cats are designed for engine and smog ,in one countries laws.
reset the all DTC errors via button on scan tool;
then drive see if P0420 comes back, first
not buy $400 cat on a whim./
I roll the dice, see 10, 2010
and answer. and LY7 engine V6 (there are others)

DTC P0420: Catalyst System Low Efficiency Bank 1
DTC P0430: Catalyst System Low Efficiency Bank 2


bank 1 means , that bank that contains cylinder #1
where is cylinder #1 it on all V engines, that cylinder that is MOST forward.
all cyl 1 are offset front

never post about cars and no year or engine told or post #8th digit of VIN this is engine code, so answer and be correct. (USA answer me only)

• DTC P0171 Fuel Trim System Lean Bank 1
• DTC P0174 Fuel Trim System Lean Bank 2
.
The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop, the ECM determines fuel delivery based on sensor signals without oxygen sensor (O2S) input. During Closed Loop, the O2S inputs are added and used by the ECM to calculate short and long term fuel trim (FT) fuel delivery adjustments. If the O2S indicates a lean condition, FT values will be above 0 percent. If the O2S indicate a rich condition, FT values will be below 0 percent. Short term FT values change rapidly in response to the heated oxygen sensor (HO2S) voltage signals. Long term FT makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. If the ECM detects an excessively lean condition, DTC P0171 or P0174 sets.
Diagnostic Aids
• Excessive resistance in the fuel injector ignition 1 voltage circuit or the fuel injector control circuit may cause the following symptoms:
- Lean condition
- Misfire
- Rough idle
• The system will go lean if an injector is not suppling enough fuel.
• A lean condition could be present during high fuel demand.
• A malfunctioning MAF sensor can cause this DTC to set. Refer to DTC P0101 .
• Review the Failure Records with a scan. If an intermittent condition is suspected, refer to Intermittent Conditions .

DTC Descriptors
This diagnostic procedure supports the following DTCs:
• DTC P0420 Catalyst System Low Efficiency Bank 1
• DTC P0430 Catalyst System Low Efficiency Bank 2

This code could mean the catalytic converter on that bank has failed .

Causes of lean condition trouble codes P0171 P0174 GM 5 3L

P0420 P0430 catalytic converter catalyst inefficiency code diagnosis

Both codes mean the computer does not think the catalytic converter(s) are working correctly. The data is based on what the O2 sensors are sending to the engine computer.
There could be a problem with one of the cats, or one of the O2 sensors. You would need someone with a scanner that could watch the data stream from the sensors to figure it out.

p0420 and p0430 both indicate a clogged catalytic converter. the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. The p0010 indicates camshaft sensor. The camshaft sensor may be the main problem, as it will affect your timing and fuel/air ratio, which in turn can effect what your Oxygen sensors detect, throwing the p0420 and p0430.

Make sure your car is timed correctly by the timing chain/belt, reset light, then if it dont' solve the problem, change oxygen sensors, if those don't help, catalytic converter is clogged.

Hi there:

DTC P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
DTC P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

Could be some electrical problem, check wires and harnesses connections (cleaning job); also check description and testing HERE.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

ok lets do this in order
P0420 Catalyst System Efficiency Below Threshold (Bank 1) an o2 sensor bad usually before the Cat converter P0430 Catalyst System Efficiency Below Threshold (Bank 2) same thing but the sensor after the cat converter the c1734 people will say you need to replace a bad BCM, but don't,, once the O2 sensor problem is addressed , that code will clear , it has to do with the remote start b2090 has to do with power doors ,, this will drop off too once the system is rest , same with the last one you listed, If I was you I'd have the 2 O2 sensors checked, replace the bad one, or both, and have the mechanic clear all the codes, then recheck them

O2 sensors are a possible cause. It has one converter, but 2 oxygen sensors...1 upstream, and 1 downstream of the converter. Which means one is very easy to get to (under the hood, on the manifold), and one is not. Usually the check engine light will come on if O2 sensors are faulty.

Code P0430 - For Continuous Memory Only -- Check for missfire detection monitor (dtc) -- Bank 2 catalyst system effciency is below acceptable threshold -- possible causes are
-Faulty HO2S
-Faulty ETC sensor
- High Fuel Pressure
- Damaged exhaust components
- Oil Contamination
- Cylinder Missfire
- Downstream O2 sensor improperly connected
- Retarted Spark Timing
Most times the problem is the Downstream O2 sensor is defective

codes p0420 and p0430 are both post o2 sensors, the ones after the convertor, both sides if replacing