P0141 Code - Which o2 Sensor

Rusty Shackleford

New member
I have read through the sticky on the o2 sensors, but I just want to be sure I get the right one because of all the confusion involved with that thread. The code that's causing my CEL to be on is P0141, which AutoZone's printout says is the "heated oxygen sensor - bank 1, sensor 2". Is that the upstream or downstream sensor?

I was under the truck today and I'm 99% positive I only saw one catylitic converter, which means I do not have Cali emmisions, correct? I'll check again when it's light outside to be sure.
 
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Bank 1 should be the first o2 sensor from the engine.... In other words closest to the engine. Correct me if I'm wrong anyone.
 
I have read through the sticky on the o2 sensors, but I just want to be sure I get the right one because of all the confusion involved with that thread. The code that's causing my CEL to be on is P0141, which AutoZone's printout says is the "heated oxygen sensor - bank 1, sensor 2". Is that the upstream or downstream sensor?

I was under the truck today and I'm 99% positive I only saw one catylitic converter, which means I do not have Cali emmisions, correct? I'll check again when it's light outside to be sure.

DO NOT GET A BOSCH SENSOR!!!!!

ONLY DENSO. The Bosch will NOT work with the truck.

Bank 1 should be the first o2 sensor from the engine.... In other words closest to the engine. Correct me if I'm wrong anyone.

Bank 1 Sensor 2 is the rear sensor.
 
So would that be the Denso 234-4162? Assuming I do not have CA emissions

Correct.

The difference between the Cali emissions and the Federal emissions is the FRONT sensor.

The front sensor on a Cali Emissions truck is an Air/Fuel Ratio sensor.

The Federal truck has BOTH O2 sensors, SAME ones.

If you can plug the rear one into the front one, its a O2 sensor. If it doesn't go in, it's an A/F Ratio sensor.
 
Correct.

The difference between the Cali emissions and the Federal emissions is the FRONT sensor.

The front sensor on a Cali Emissions truck is an Air/Fuel Ratio sensor.

The Federal truck has BOTH O2 sensors, SAME ones.

If you can plug the rear one into the front one, its a O2 sensor. If it doesn't go in, it's an A/F Ratio sensor.

Awesome, thanks man!
 
Correct.

The difference between the Cali emissions and the Federal emissions is the FRONT sensor.

The front sensor on a Cali Emissions truck is an Air/Fuel Ratio sensor.

The Federal truck has BOTH O2 sensors, SAME ones.

If you can plug the rear one into the front one, its a O2 sensor. If it doesn't go in, it's an A/F Ratio sensor.

Ok, so I just crawled under the truck and looked and I do have 2 catalytic converters. Does this mean that my truck has CA emissions?

And the sensor towards the rear of the vehicle is definitely longer than the one in the front. Is this still the Denso 234-4162?
 
Ok, after another trip underneath the truck, this time with a tape measure, the front measures roughly 13". This is an Air/Fuel Ratio sensor, correct? Denso shows two part #'s, 234-9002 & 234-9003, which one do I need? I think I'm going to go ahead and replace both sensors just to be safe. The front one looks pretty rough at the attachment areas.

The rear measures roughly 18", which from reading the sticky thread looks like it's Denso # 234-4153.

Can someone please confirm these numbers?
 
From Oxygen / AFR Sensors - Underdog Racing Development

1999 & 2000 Cali auto, 4WD V6; Front: 234-9002
1999 & 2000 Cali auto, 4WD V6; Rear: 234-4153

9002 is an A/F and has a wire length of 12", 4153 is O2 and has 17.7"

234-9003 is for the 5spd (my truck) and has w/l of 16.5".

Yes, two cats means Cali. emissions (in '99 and 2000, plus all '01+) and means A/F sensor in front.

To confirm, look at emissions label--top left corner. If the letters say A/F S, TWC(2), HO2S, it's a Cali:

CDF10125-BEEC-48C6-B9EC-B7AF9FA9025D-3268-0000030ACE6A514A_zpsb6574bc0.jpg


If it's a Federal/50-state/Non-Cali (pre-2001) it will say: HO2S(2), TWC

Emissions%2520Sticker.jpg


Don't read the paragraph in the box, they change every year and are very confusing.
 
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Let's hope the bolts holding it in are not seized or rusted down!

Unless you have a Cali model you should have two identical sensors. I hope you follow the Denso advice!! OEM or nothing for me!

Best of luck!!
 
Last edited:
From Oxygen / AFR Sensors - Underdog Racing Development



9002 is an A/F and has a wire length of 12", 4153 is O2 and has 17.7"

234-9003 is for the 5spd (my truck) and has w/l of 16.5".

Yes, two cats means Cali. emissions (in '99 and 2000, plus all '01+) and means A/F sensor in front.

To confirm, look at emissions label--top left corner. If the letters say A/F S, TWC(2), HO2S, it's a Cali:

CDF10125-BEEC-48C6-B9EC-B7AF9FA9025D-3268-0000030ACE6A514A_zpsb6574bc0.jpg


If it's a Federal/50-state/Non-Cali (pre-2001) it will say: HO2S(2), TWC

Emissions%2520Sticker.jpg


Don't read the paragraph in the box, they change every year and are very confusing.

Thanks for all the great info! Very helpful. I'll be ordering the Denso's today
 
Let's hope the bolts holding it in are not seized or rusted down!

Unless you have a Cali model you should have two identical sensors. I hope you follow the Denso advice!! OEM or nothing for me!

Best of luck!!

Oh yeah, bolts on the rear one are almost rusted away. Gonna be fun for somebody
 

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