As a California smog tech i do a lot of 02 sensors.Japanese sensors can be very different than German.On a recent Jeep ,1999,with a new ND sensor,the jeep had 1,000 nox,when changed to bosch nox dropped to almost 0.This does not happen all the time but often.
Also if a new 02 still has CO that is not as low as it should be we order a new 02 and now the readings are perfect.So new 02s can be off a little or alot ,but correct brands are very important.Having a smog machine to verify tailpipe readings can be very helpful.
On 3 wire sensors that have to be spliced DO NOT USE THEM.Have tried about 10 of these and gave up.These go in older BMW,PORSCHE,AND Benz.some work for a short time or not at all.CO does not stay steady or goes nuts.Direct fit 02s are much cheaper than a cat converter'
How many bad 02s throw codes on pre1996 cars is just about 0
Rich

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88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car