The engine light is on and the code is P0420 – Catalyst System Efficiency Below Threshold Bank . What part do I need to fix it?

ANSWER : While a number of things like a faulty oxygen sensor or exhaust leak can cause fault code P0420 to be set, the most common fault is the catalytic converter itself. However, as a replacement can be very expensive, your best be is to have a certified technician properly diagnose why code P0420 was set in the system.

ANSWER : The P0011 code is typically caused by oil issues with the car. I would particularly make sure the engine oil level is not low. The VVT solenoid relies on proper oil levels to do their job. If they don’t have enough oil, they won’t work. You can have a mobile technician from YourMechanic visit your home or office to inspect the Check Engine Light for you. If you follow through with a repair with us you will be reimbursed for the cost of inspection.

ANSWER : Hello. If the oil level was low or if the wrong oil war previously used then that can cause these codes to come up. Most of the time though, on this engine, it is caused by a failure in the timing chain. The timing chain is the most common failure on this engine and when it is stretched enough the cam timing will be off enough to cause this. If you want to have this camshaft timing looked at, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose why the check engine light is still on and address any issues that are found.

ANSWER : Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system.

Since this fault has lasted after the engine was replaced it could be a oil pressure sensor, wiring harness fault, ECU fault, oil pump, oil strainer clogged, or low oil pressure.

To diagnose this issue properly you need a complete vehicle inspection to start from square one and identify the root cause of all this.

ANSWER : It is possible that you could be having an issue with your powertrain control module. This is somewhat of a common problem on many GM vehicles. I would recommend having your vehicle inspected by the dealership to determine if the powertrain control module is functioning properly. If not, a reflash of the powertrain control module may resolve the issue but often times it must be replaced.

ANSWER : Hi there:

One of the major problems car owners have with mechanics or dealerships specifically is that they really don’t go the extra effort to fix all issues with a vehicle. In most cases, they’ll receive a complaint from a customer, (such as the car won’t start), and they’ll fix that specific issue without downloading all stored error codes and letting them know of all issues with the vehicle. This can be avoided by having a mobile mechanic complete a check engine light inspection; before you head to a mechanic shop or a dealership. This will allow you to get a big picture perspective about what’s really going on with your vehicle, what needs to be repaired and what’s causing issues. Taking this proactive step can save you a tremendous amount of time, money and reduce frustration.

ANSWER : If a faulty component is still in place, the fault codes will return almost immediately after clearing them. ABS, ESP, and traction control systems all rely on input from wheel speed sensors to determine as the name implies, the speed of each wheel. When a wheel, or wheels are spinning faster than others due to wheel slip or the vehicle is sliding, the ABS and ESP systems can reduce throttle input as well as apply braking to an individual wheel or all of them if needed. With a wheel speed sensor fault code stored, these systems cannot determine the rate that all 4 wheels are spinning and sets a fault. That is why the abs/esp light is on. The system should be scanned by a certified technician and the wheel speed sensor replaced if found to be the cause. The warning lights will stay on and these systems will not function as designed until the fault is corrected. These lights do not come on to indicate a need for routine service. Rather they only come on when a component in the system is at fault.

ANSWER : Hi there. Typically the P0420 OBD II trouble code is caused by a faulty catalytic converter, however it can also be due to a worn out front bank O2 sensor, faulty rear O2 sensor or damage to wiring harnesses to sensors. If you smell a rotten egg smell while driving, it’s likely the catalytic converter that will require replacement. Without knowing exactly what is causing the failed smog test, it’s very difficult to give you an estimate on repairs. The best way for us to attempt the repairs is to first complete an onsite check engine light inspection so our mechanic can download all stored error codes (beyond the P0420 code) that could help pinpoint the primary source of this issue.