A P0426 trouble code is related to one of a vehicle’s catalytic converters and the temperature range that is deemed normal by the manufacturer.
What the P0426 code means
P0426 is an OBD-II generic code for a threshold problem with a vehicle’s bank 1 catalytic converter. This is the part of the exhaust that helps reduce emissions for either the entire engine, or just the bank of cylinders that includes cylinder one. The engine computer rates its efficiency by way of the oxygen sensor. If the data being sent by the sensor to the computer is not within the manufacturer’s parameters, a check engine light is illuminated with a P0426 code.
What causes the P0426 code?
The most common causes for a P0426 are:
- Faulty oxygen sensor
- Faulty catalytic converter
- Damaged oxygen sensor wiring
- Exhaust leak
- Poor quality gas
What are the symptoms of the P0426 code?
More often than not, a P0426 will simply result in a check engine light as it won’t take much for one to be triggered. In some cases, the catalytic converter can be physically damaged which would result in a lack of engine performance, stalling, and poor fuel mileage.
How does a mechanic diagnose the P0426 code?
Your mechanic will first visually inspect the catalytic converter and the oxygen sensors to ensure they seem to be in good condition and to rule out one or the other as a cause. A faulty catalytic converter will usually give itself away from an audible rattle when hit with a small hammer. If the oxygen sensor wiring appears damaged, the entire sensor may need to be replaced.
If the trouble code is present with no noticeable symptoms, the P0426 may be an intermittent code that could be dealt with by simply resetting the engine computer.
Common mistakes when diagnosing the P0426 code
While a P0426 does literally say “catalyst,” the catalytic converter is not always to blame. Because the oxygen sensor has to relay the data to the engine computer before it can confirm there’s a problem, a faulty sensor can cause a number of issues.
How serious is the P0426 code?
Unless a P0426 is causing adverse driving conditions associated with a faulty catalytic converter, most codes are no more serious than a “service engine soon” light. Even still, all problems should be investigated as quickly as possible to ensure no critical damage to the vehicle’s exhaust and emissions system.
What repairs can fix the P0426 code?
The most common repairs for a P0426 are as follows:
- Replacing the oxygen sensor
- Replacing the catalytic converter
- Repairing damaged oxygen sensor wiring
Additional comments for consideration regarding the P0426 code
P0426s are commonly associated with other trouble codes. If you do encounter multiple codes, always make sure to pay close attention to how they show up on an OBD-II scanner as the order can indicate what the actual route of the problem is.
Need help with a P0426 code?
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