Changed catalytic converter, no lights on dashboard, but codes for catalytic converter & O2 sensor still remain
Changed catalytic converter, no lights on dashboard, but codes for catalytic converter & O2 sensor still remain
My car has 129000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hi there, thanks for writing in. I am not sure why you changed your catalytic converter. Assuming you had a P0420 code, replacing the catalytic converter should of resolved that code. The codes originally stored need to be cleared. The fact your check engine light remains off tells me, you may have fixed the problem. Try disconnecting the negative battery terminal for at least 2 minutes, reconnect. Start and drive the vehicle for 10-15 miles. Re-check for codes. If a code returns on the first drive cycle (pending code), a problem still exists. The check engine light should come back on (the next drive cycle) if, the fault is recognized by the computer. An exhaust leak before the oxygen sensor will cause O2 sensor and catalytic converter codes. If you are having trouble identifying the fault, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
The code P0420 can be caused by the catalyst, O2 sensors before and after the catalyst. If both O2 sensors and catalyst was replaced then you may have an exhaust leak at the manifold or pipes.
Does removing a catalytic converter trigger a check engine light? Yes, if you gut it or straight-pipe it, the downstream O2 sensor after the cat would show the same/similar reading as the upstream O2 sensor before the cat. This would trigger a check engine code for catalytic converter efficiency below threshold.
Code P0420 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.
Yes, the oxygen sensor can damage the catalytic converter, although the damage is indirect. What actually happens is that the oxygen sensor malfunctions and sends incorrect data to your vehicle`s main computer chip.
A P0420 code is set when the upstream sensor and the downstream oxygen sensor sense the catalytic converter is not doing its job. Basically, the amount of oxygen going into the converter is not being burned, and it detects it through the downstream sensor.
The most common mistake is replacing the oxygen sensors before completing the diagnostic process. If another component is causing the P0420 trouble code, replacing the oxygen sensors will not fix the problem.
Driving with A Failed Catalytic Converter
If you`re noticing slow powertrain performance, reduced acceleration, a smell of rotten eggs or sulfur from the exhaust, dark exhaust smoke, or extreme heat from under the vehicle, these are symptoms of a clogged Catalytic Converter, and it should be replaced quickly.
A failing catalytic converter is a common cause of check engine lights turning on, and it can lead to a decrease in fuel economy and engine performance.
Repair Urgency: Get this code fixed as soon as possible to avoid further damage to your emission system and possible engine damage. Diagnosis: The most common cause of P0420 is a bad catalytic converter, but it can be caused by anything from a faulty oxygen sensor to a rich or lean running condition, or misfires.
Even a small leak anywhere in the exhaust system can draw a significant amount of oxygen into the system. Since catalytic converters have limited oxygen storage capacity, the rear O2 sensor will detect the excessive oxygen and generate a converter efficiency code.
Not necessarily. For example, if the catalytic converter fails because of cracked welds or because the element inside broke up into tiny pieces, the oxygen sensors will be fine (usually there`s an upstream and a downstream oxygen sensor in modern vehicles).
The role of the downstream sensors is to monitor the output and health of the catalytic converter. Removing them will take away this function, and produce a CEL (check engine light) or MIL (malfunction indicator light) on the vehicle.
A common emissions code seen in the field, a P0420 trouble code indicates that the catalytic converter isn`t functioning efficiently.
Cycle the ignition OFF/ON 2 times with a 10 second pause in between key cycles. Check measured value block (MVB) 41/4 and 136/4 to verify they have both changed from a 1 to a 0. This forces the ECM to re-learn the O2 sensor adaptation.
Yes. Bad spark plugs can cause a P0420 code because when one or more spark plugs are faulty, they are not able to ignite the air and fuel mixture in the combustion chamber so the unburnt mixture, along with the Nitrogen Oxide and Carbon Monoxide from the combustion chamber will go into the catalytic converter.
However, failing to clear a code after a repair could leave you second-guessing the issue or doubling your work to recheck the codes. That`s why you should always make clearing codes an essential part of your repair process.
There is no such thing as resetting an oxygen sensor. Once the problem related to the oxygen sensor code has been properly diagnosed and repaired the car`s computer will turn the light off and erase the code. The computer will do this when it sees two consecutive drive cycles with the problem corrected.
A bad catalytic converter will give off higher emissions than allowed by the state. So a car with a malfunctioning catalytic converter will not pass a vehicle inspection. And that means you won`t be able to drive your vehicle legally.
Most catalytic converter failures fall under one of three categories: Overheated, melted or broken converters.
What Are Potential Issues With a Catalytic Converter? Catalytic converters often last for 10 years or more, but they can become contaminated, clogged, overheated or physically damaged — leading to sluggish engine performance and, eventually, engine shutdown.
It`s important to say that Cataclean cannot repair a part that has failed due to an excessive buildup of carbon. If the check-engine light stays on even after use of Cataclean, for example, then it`s possible that the damage to the catalytic converter is irreversible.
The p0420 code means that the catalytic converter is below threshold and is not functioning correctly. This code comes up when the catalytic converter can no longer burn off any fuel in the exhaust system.
But not always. it could be caused by an exhaust leak in or around the converter. Or, it could be related to a faulty A/F Sensor (front oxygen sensor).
A new catalytic converter should last for around 10 years but, as with most other vehicle components, the exact lifespan can differ. Mileage and engine tune can impact on the durability of the item, so it`s worth checking the condition after 50,000 miles.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Changed catalytic converter, no lights on dashboard, but codes for catalytic converter & O2 sensor still remain
ANSWER : Hi there, thanks for writing in. I am not sure why you changed your catalytic converter. Assuming you had a P0420 code, replacing the catalytic converter should of resolved that code. The codes originally stored need to be cleared. The fact your check engine light remains off tells me, you may have fixed the problem. Try disconnecting the negative battery terminal for at least 2 minutes, reconnect. Start and drive the vehicle for 10-15 miles. Re-check for codes. If a code returns on the first drive cycle (pending code), a problem still exists. The check engine light should come back on (the next drive cycle) if, the fault is recognized by the computer. An exhaust leak before the oxygen sensor will cause O2 sensor and catalytic converter codes. If you are having trouble identifying the fault, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.
check engine light O2 sensor already replaced same codes still popping up after replacing old O2 sensor
ANSWER : Hi there. What you received from the parts store was a code retrieval, not a diagnostic. The codes are set when a fault is detected against normal operating parameter. The computer does not know what caused the fault, only that the fault meets the criteria for this code to set. There could be a problem in the wire harness, converter, or the ECM. The code and data are needed to properly assess the direction that a diagnosis needs. I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection.
O2 sensors changed, but check engine light still showing code after clearing it I checked fuse. Wires are good and used Denso OE.
ANSWER : Depending on what the code was for will determine if the oxygen sensor was to be replaced. If the conditions were for a rich or lean mixture and it said oxygen sensor, then the spark plugs and wires could need replaced if its a rich reading or the fuel injectors could be clogged or not working if its a lean mixture. If the code said that the oxygen sensor was bad, then check the harness and see if there is a break in the wiring or a short to ground in the wiring from the oxygen sensor to the main harness. If you need further assistance with your check engine light being on, then seek out a professional, such as one from Your Mechanic, to help you.
Diagnostic code read o2 sensor bad, replaced o2 sensor, cleared code but engine light came back on, is it caused by bad air filter
ANSWER : Hello there. Typically jump starting a vehicle doesn’t trigger an OBD-II error code. However, one of the most common misdiagnosis issues with the P-2270 is replacing the O2 sensor before diagnosing if there are any exhaust leaks. Obviously, you’ll want to check for the exhaust leaks first, repair the damaged component, and then clear the codes before scanning the vehicle again. Sometimes the electrical harness attached to the O2 sensor is damaged or dirty which will also trigger this error code. The noise and vibration may be an indicator of a loose exhaust pipe, which may be the source of the error code staying on. If you need any help, have a technician from YourMechanic come to your home or office to diagnose your Check Engine Light and make the necessary repairs.
Check Engine light comes on, mechanic replaced o2 sensor but light still comes on.
ANSWER : Hi there:
If the mechanic completed the O2 sensor replacement, reset the codes and the error code was triggered again, it is possible that the catalytic converter is damaged and needs to be replaced. However, it’s also very common for the electrical harnesses that power these sensors to become frayed, damaged or faulty; which can also trigger the check engine light. It’s not advisable to drive a vehicle with a damaged catalytic converter for extended periods of time, as it can cause damage to internal engine components.
Service engine warning, MAF code and O2 sensor code, along with check suspension light are turned on
ANSWER : Hello, it sounds like you have quite a few things going on. I am going to do my best to break them down for you.
First if the engine is very loud when idling and the belt has already been replaced, there may be an issue with the tensioner or idler pulley.
Next, the Navigator is known for needing service to the air suspension system as it gets up in miles, the most common causes of these are the air struts themselves have failed, or one of the air lines has a leak.
Lastly, if the O2 sensor and MAF are continually coming back after the sensors have been replaced, the most common cause would be either an exhaust leak or a vacuum leak.
Qualified technicians such as the ones at YourMechanic will be able to diagnose these issues and recommend the best path to repair, starting with a diagnosis of your warning lights.
So I had two codes come up for two of my o2 sensors..replaced them both and check engine light is still on…my mechanic seems to
ANSWER : Hi there:
Although it’s hard to say if there was serious damage done to your ECM during this service, it’s more likely that the stored error codes were never cleared from the ECM, and that’s why the warning lights still appear. This is a common oversight with some mechanics, but if you have a mobile mechanic complete a check engine light inspection, they should be able to clear those stored codes and determine if further damage has occurred.
I have changed the MAF sensor, oxygen sensors, gas cap, catalytic converter and I still get check engine light.
ANSWER : Hello, thank you for writing in. With a check engine light on, the first step is to have the vehicle scanned for diagnostic codes. This can be done by a technician, or at most auptmot8ve parts stores. That information will guide you to the system or component having issues. Your symptoms may be caused by an EGR problem, fuel system problem, or a variety of other issues. Ignition system malfunctions can also cause similar symptoms. Only further inspection will tell. For more help with testing contact our service department to schedule an appointment.
