I recently purchased a 2018 Expedition Limited with a bad motor with 140,000 miles. I replaced the engine purchased from a salvage yard with 45,000 miles. It runs great besides it throwing a P0430 code. I can clear the code and it comes back about every 20 miles or so. I checked live data on a scanner and it’s showing high resistance on both upstream O2 sensors. I don’t want to go throwing a converter on it till I figure out why the resistance is high on the O2s. Freeze frame data for the P0430 code is also showing intake air temperature sensor bank 1 sensor 3 was at -40. I’ve replaced all 4 O2 sensors with motorcraft sensors and nothing changed. I figured with 140k it wouldn’t hurt to change them regardless. I’ve swapped out the map/air temp sensor with the one from the core engine I still have. Checked wiring over and over again I’ve cleaned the grounds and still nothing. It’s driving me crazy trying to figure this out. Has anybody seen anything like this or have any advice?
New here and looking for help with my 2018 Limited. P0430 code with high resistance O2 sensors.
- Thread starter Luke1722
- Start date
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DieselMonk
Full Access Members
Fix that -40f temp sensor. Take a DMM and measure the volts on the O2’s before and after the cats and compare them. Does the exhaust have a rotten egg smell, or does it smell quite rich in fuel?
My scanner is saying intake air temperature bank 1 sensor 3 does anybody know where sensor number 3 is?
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DieselMonk
Full Access Members
Should be passenger side, oxygen sensor after the cat (last sensor), I believe.
Mr Big
Full Access Members
I had the same o2 sensor error code issue with my 2019 Expedition. I would clear it and it would come right back. Someone on the forum posted that using Liqui Moly Catalytic System Clean clears up the possible gunk on the tips of the sensors. I bought a bottle, followed the directions, cleared the error codes and my error code never came back. You may have a different issue but it may be worth a try. It's definitely cheaper than a cat converter.
I just remembered I had this recall performed: PCM Recall that may help your error code issue, as well as other issues.
I just remembered I had this recall performed: PCM Recall that may help your error code issue, as well as other issues.
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