P0420 code repeat
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On The Tree
Joined: Dec 2013
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P0420 code repeat Hello,
Recently had left side cat converter replaced because vehicle was throwing P0420 code. I had previously replaced MAF Sensor and Upstream O2 Sensor. The car ran for about a month + with no P0420 code in sight. Recently started throwing the P0420 code again. I am wondering what it could be. Is is possible to check the cat converter to see if it's bad? Or is it [as a friend says it probably is] the downstream O2 Sensor? Or is it something else altogether.
Any ideas? The car goes like a scalded cat, but has not been getting very good mileage [14-15, more towards 15].
Thanks,
fastertransam
Recently had left side cat converter replaced because vehicle was throwing P0420 code. I had previously replaced MAF Sensor and Upstream O2 Sensor. The car ran for about a month + with no P0420 code in sight. Recently started throwing the P0420 code again. I am wondering what it could be. Is is possible to check the cat converter to see if it's bad? Or is it [as a friend says it probably is] the downstream O2 Sensor? Or is it something else altogether.
Any ideas? The car goes like a scalded cat, but has not been getting very good mileage [14-15, more towards 15].
Thanks,
fastertransam
Hello,
Recently had left side cat converter replaced because vehicle was throwing P0420 code. I had previously replaced MAF Sensor and Upstream O2 Sensor. The car ran for about a month + with no P0420 code in sight. Recently started throwing the P0420 code again. I am wondering what it could be. Is is possible to check the cat converter to see if it's bad? Or is it [as a friend says it probably is] the downstream O2 Sensor? Or is it something else altogether.
Any ideas? The car goes like a scalded cat, but has not been getting very good mileage [14-15, more towards 15].
Thanks,
fastertransam
Recently had left side cat converter replaced because vehicle was throwing P0420 code. I had previously replaced MAF Sensor and Upstream O2 Sensor. The car ran for about a month + with no P0420 code in sight. Recently started throwing the P0420 code again. I am wondering what it could be. Is is possible to check the cat converter to see if it's bad? Or is it [as a friend says it probably is] the downstream O2 Sensor? Or is it something else altogether.
Any ideas? The car goes like a scalded cat, but has not been getting very good mileage [14-15, more towards 15].
Thanks,
fastertransam
Teching In
Joined: Nov 2020
Posts: 2
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From: Santa Clara
PO420...Catalyst System Efficiency Below Threshold, bank 1.
You have an oxygen sensor in front and behind the cat converter, among others. When the engine is warm and in closed loop mode, the front oxy sensor reading should fluctuate, and the rear oxy sensor should read more steady. If the two sensors have similar readings, it means the cat converter isn't working correctly, and it will trip an error code.
Did you gut the cat, remove the cat, or mess with the oxy sensors at all? If you haven't enough money to fix it - take a cash advance on the Maybeloan and don't worry.
You have an oxygen sensor in front and behind the cat converter, among others. When the engine is warm and in closed loop mode, the front oxy sensor reading should fluctuate, and the rear oxy sensor should read more steady. If the two sensors have similar readings, it means the cat converter isn't working correctly, and it will trip an error code.
Did you gut the cat, remove the cat, or mess with the oxy sensors at all? If you haven't enough money to fix it - take a cash advance on the Maybeloan and don't worry.
Last edited by Faladarin; Dec 2, 2020 at 11:04 AM.
