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Discussion Starter · #1 · (Edited)
I've researched this for hours but can't find any info on O2 sensor position.

I first installed Denso sensors 234-1017 (right) and 234-1006 (left) incorrectly, thinking the left sensor was on the left side of the exhaust manifold as I faced the engine.

I reversed the position of the sensors when I realized my mistake but I'm suspicious because the lead of the left sensor (as reinstalled) is the shorter of the two leads and does not reach far enough to plug into the connector mounted on the engine. I had to remove the connector from the mount to enable the sensor lead to reach it. (The other connector is just as far away ....)

This is seeming like a "clue" that the sensors aren't in the right position.

Q1 -- Are the sensors in the right location?

Q2 -- Does it make any difference?

"Luzer" in one of the 3rd Gen threads on O2 sensors said there's no difference between the two sensors on a B20A5 engine, which I assume is what I have.

I've think I've got a bad engine coolant sensor and a possible bad connection with Sensor A (right sensor) but I want to make sure the O2 sensors are in the right place before I try to troubleshoot other problems.
 

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The two sensors are identical, at least mine are. But it may matter which one goes into which position as far as the connectors are concerned. On mine, the green connector is for the sensor on the passenger side, and the white connector goes to the sensor on the driver's side (LHD).
 

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Hmmm. Mine is set up in reverse of Luzer's, green is driver's side ( for left hand drive cars). The only real difference is that trouble codes reported by the ECU (codes !-2) could guide you to the wrong sensor. I have no idea which is correct. The manual says sensors "A" and "B" while we are saying white and green. The manual says driver's side is "B". Try this... disconnect the driver's side and the ECU should give you a code "2". This means that when looking at the sensors from over the front bumper...sensor A (or code 1) is on the left and sensor B (or code 2) is on the right. This is opposite of the usual orientation which calls left and right by sitting in one of the front seats. Is your head spinning yet ? Hahahaha.
 

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Discussion Starter · #4 ·
Identical

Thanks, Luzer. I think you're right. It's not like the ECU would need a different measurement of oxygen content, especially when the sensors are so close together and in essentially the same stream of exhaust gas. It's not like one of them is placed after the catalytic converter where something happens that changes the nature of the exhaust gas.

NAPA store clerk also told me that other manufacturers that provide sensors for my particular Honda have the same part number for both left and right sensors.

The connector is the same for either sensor.

I appreciate your help.
 

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Discussion Starter · #5 · (Edited)
Not spinning

Thanks, Dano. No, my head's not spinning. That's actually quite clear. I'm going to switch the sensors, reset the ECU, and see what's what. I was getting a code 1 yesterday but today both 1 and 2, but with rough operation between 2500-3300 rpm. After 3300, engine would suddenly smooth right out.

I need to try swapping my coolant sensor before I confuse matters by getting into this aspect of my problem. I'm hoping (against reason) that a transient indication of a coolant sensor problem is pointing to that sensor possibly causing my problem, but we shall see. I'll know tomorrow.

I appreciate your help.

PS -- I have about 425,000 on my '89 and have been plagued by oil and power steering fluid leaks so I have a fairly grimy engine compartment but yours is ridiculously clean. How do you manage that?
 

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Your engine bay looks great dano. Is that a magnetic parts tray I spy near the rad fan?
 

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Discussion Starter · #9 ·
I switched the O2 sensors so the short lead wasn't overextended and fixed a broken wire to the coolant temp sensor. My CEL codes for something bad re O2 sensors went away when I made sure that the connector on the lead from the sensors was crimped down tight so it would really grip the blade inside the male connector. No more CEL and mpg leaped from 28 to 33.7.

Thanks again for all the help.
 

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Wow might have to try this out because I get like 23 mpg on street and 25 mixed.
 

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Discussion Starter · #11 ·
Wow might have to try this out because I get like 23 mpg on street and 25 mixed.
I understand O2 sensors have a big effect on mileage and I can attest to about a 5 mpg drop when I get an ECU code for just one O2 sensor.

I read on one of the Honda forums somewhere (IROOOTHFS) that an overly rich fuel mixture can occur even if your O2 sensors are good.
 
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