What does P0420 code mean ?
P0420 means that Catalyst system efficiency below threshold (Bank 1). P in the p0420 abbreviation of "Powertrain". This group of OBD/2 codes is related in engine troubles. P0420 is an inefficient catalytic convertor code.
If your vehicle mileage is less than 50K miles, catalytic converters typically don't just go bad at that many miles. There is likely something else going on. Often it is an injector dumping or leaking excess gas into the engine. Or the dealer could have used some sort of cleaner that damaged it. You really need to know exactly what these shops are doing because modern vehicles are not very tolerant of some old school "tune up" methods. The fact that it happened after they worked on it seems unlikely to be a coincidence.
What causes a P0420 code ?
A bad cat (common) or O2 sensor(s) are the most likely causes P0420, followed by an exhaust leak between the header and cat (flex pipe).
Or being a vacuum leak causes P0420.
Or the vehicle may be having some type of spark knock.
Also check the flex pipe between the exhaust and the catalytic converter for leaks/damage. The exhaust flex pipe in the Sonic takes a lot of abuse being so near the roadway/ground and rust apart causing the sensors throw this P0420 code.Or check the list please :
- Fuel quality (low-quality fuel a/k/a Murphy Gas)
- Fuel quantity (filter or pump issue)
- Ignition issues (plugs, wires, coils injector flow)
- Temperature control (too high or too low)
- Vacuum leaks
- Exhaust leaks (not only an annoying noise, but it also affects proper value reporting to the ECM by the AF and O2 sensors)
- Poor amperage conductivity (i.e. battery or cabling)
- Faulty Catalytic Converter: The converter may be damaged or worn out.
- Oxygen Sensor Issues: Malfunctioning or faulty O2 sensors can provide incorrect readings.
- Exhaust System Leaks: Any leaks before or after the catalytic converter can affect its efficiency.
- Engine Misfire or Poor Fuel Quality: These issues can damage the catalytic converter.
- Faulty Wiring or Connectors: Issues with the wiring connected to the O2 sensors or catalytic converter.
If the main reason is bad cat , these reasons can cause it : bad AFM cylinder, leaky injector or low octane gas.
P0420 Symptoms :
Check engine light shows an engine error, when you diagnose it with obd scanner you can see p0420 code , so the first symptom is catalytic converter not working properly.
Another symptom is ECU is not pulling any timing or fuel to manage the poor catalyst efficiency.
How to fix P0420 code ?
Check O2 sensors are oscillating between 0.200 and 0.800 volts if it is fine the problem is in cat. converter.
Another advice : Replace battery cables, buy a new fuse bus and greased all connections, cranked the car and the code immediately will disappear.
Easy way to do is replacing the catalytic convertor with the new one. Yes it can be expensive but for your vehicle health and engine condition to prevent other fault codes it will be the best way.
Common Mistakes P0420 Fixing Procedure :
-O2 sensors MUST be OEM (and must be the correct part numbers: there are two different upstream/bank 1 O2 sensors for these engines and I believe they both fit. Use your VIN when ordering).
-Vacuum system MUST be completely sealed.
-Check your flex pipe with a flashlight. It can be easy to mis small cracks/tears.
-Who is resetting your codes and how are they doing it? They need to be able to read live data with a scan tool. There is no other way to perform a complete test of the electronics that are impacting that code. In other words, a code reader is not sufficient.
-The factory service manual states that your code may still return for approximately the first 100 miles because the new materials are off-gassing/breaking in as they heat cycle for the first few times. Don't panic if the code comes on after a new catalytic converter. Drive it for 100 miles, reset the code, and see if it comes back.
How much does it cost to fix a P0420 code ?
P0420 code is a worn catalytic converter, but this can differ depending on your specific model. These can cost over $1000 .
Will P0420 code clear itself ?
After fixing/replacing o2 sensors or catalytic converter %99 it will clear itself automaticly.
Common Questions & Answers About P0420 Code
- Can a bad o2 sensor cause a p0420 code ?
Yes, a catalyst monitor uses signals from the downstream O2 sensor if it is broken the p0420 code occurs.
- What is the most common cause for a p0420 code ?
The common cause of p0420 is broken of catalytic converter.
- Will catalytic converter cleaner fix p0420 ?
Propably yes because 10 percent chance it will about dirt in catalytic converter or you have to replace it with new one.
- How to pass emissions with p0420 code ?
Passing emissions with a P0420 code can be challenging because this code is often related to the catalytic converter's efficiency.
Emissions Test: Once you've addressed the underlying issues and completed the drive cycles, take your vehicle for an emissions test.
Professional Verification: Consider having a professional verify that the issue has been resolved before undergoing an official emissions test.
- Which o2 sensor causes p0420 trouble code ?
Bank 1 (driver side) o2 sensor causes it.
- Can an exhaust leak cause a p0420 code ?
It is not the reason, it is result of p0420 error, your catalytic converter needs to replace with new.
- What does p0420 bank 1 mean ?
Bank-1 means it occurs driver's side. For example P0430 is Bank-2.
- Can a dirty air filter cause a p0420 code ?
No, it will be the result.
- Can bad spark plugs cause p0420 ?
Probably yes, %10 change it will cause P0420 fault in your car.
- Can p0420 cause misfire ?
Yes, the engine's best answer is this.
- Is p0420 upstream or downstream
In high mileage cars, it will occur downstream.
- Does cataclean fix p0420 ?
Probably yes, but you will face with the same code in future, because your cat. converter might be death.
- How long can you drive with P0420 code ?
You can drive 1-2 hours per day with in a week, but extended driving with this code can cause internal engine damage.