Questions and discussions about oxygen (O2) sensors. Oxygen sensors are used to measure the exhaust gas concentration of oxygen for internal combustion engines in automobiles and other vehicles.

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12
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1answer
96 views

Are widebands known to go lazy over time?

I know narrowbands can go lazy with time, but what about widebands? This is a sequel to the cold-start misfire mystery. It turns out that we were looking at the wrong PID's for the front O2 sensor ...
11
votes
1answer
229 views

How do lambda sensors work?

Virtually every modern passenger vehicle today utilizes lambda sensors from the factory. How critical are they to a vehicle's operation? How do they work?
11
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3answers
67k views

Check Engine code P0420 Catalyst efficiency below threshold bank 1

After months of normal driving with no problems, my 2003 Honda Civic EX check engine light came on during a long trip. Got it scanned and it's P0420: Catalyst efficiency below threshold bank 1. They ...
11
votes
2answers
202 views

Rough idle @ stoplights - O2 sensors reading zero voltage

I have an '05 4.7L Dodge Dakota that has had an issue with rough idle for over a year now. It seems to only happen after coming to a stop at a traffic light. It seems to happen more often after having ...
10
votes
3answers
841 views

Is 60/40 solder fine for splicing wires that have to endure hot engine bay temps?

I need to splice the pigtail connectors from my old O2 sensors onto the new O2 sensors since the new connectors have a different shape. As the sensor is right behind the engine and will experience ...
9
votes
1answer
8k views

Do I have to rely on wire color to correctly wire up an O2 sensor?

It seems that everyone and their grandmother has a different color-code convention for 4-wire O2 sensors, which complicates matters when one is trying to wire up a replacement "universal" O2 sensor. ...
9
votes
1answer
292 views

A most intriguing cold-start misfire mystery

I'm trying to help a friend out with a CEL on his 2009 Merc GLK 280. Hooked it up to an OBD2 reader and retrieved a single code: P0300 - 'Random/Multiple Cylinder Misfire Detected', via the 'OBD ...
7
votes
3answers
193 views

2005 Crown Victoria Police Interceptor showing codes P0053, P0054, P0059 and P0060

I have replaced all 4 oxygen sensors and OBD II code still shows codes P0053, 54, 59, and 60. What could be causing this and how do I fix it? The O2 sensors have 2 white and 2 black wires. Exactly ...
7
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1answer
75 views

Locating the O2 sensors and the cat along the exhaust

I gather that the upstream O2 sensor is the one right in the center of this picture. I also gather that the catalytic converter (the "cat") is the bulbous part of the exhaust right behind this sensor. ...
6
votes
3answers
3k views

How to Unscrew/loosen stuck O2 sensor

I have been trying to unscrew my faulty O2 sensor (to replace it with a new one I purchased) in a 2001 Honda Accord, with a F23A4 engine, per the following instructions: ...
6
votes
2answers
386 views

How to Identify which O2 sensor is faulty WITHOUT readings from the car's system

I have a 2005 Hyundai Accent, and the check engine light is on. I'm almost 100% sure it's the O2 sensor because it's not as fuel efficient as usual... My work schedule conflicts with mechanics around ...
6
votes
3answers
296 views

2002 VW GTI 1.8T - O2 sensor fault code only when exceeding 70mph

During my last roadtrip when I was driving at about 80mph on the highway (75 speed limit) a pressed the brakes abruptly after being cutoff by another vehicle, then my MIL came on. When I checked the ...
6
votes
4answers
75k views

Sputtering while driving & idling

[My car: 2004 Mazda 3] So, my wife came home from running some errands and told me the check-engine light was on and that the car was sputtering and felt like it was going to stall while stopped at ...
6
votes
1answer
40 views

Why does an engine revving at 3000 rpm produce O2 variations of 1-2 Hz?

To test whether either or both O2 sensors are damaged, one hooks the (black, following Bosch's convention) wire on each sensor and tracks the signal against the ground using an oscilloscope. When the ...
6
votes
1answer
3k views

P2238 Positive Current Circuit Low on Toyota Camry 2004

I'm getting P2238 Positive Current Circuit Low from my car, for O2 Sensor in Bank 1 Sensor 1 for my Toyota Camry 2004 (4 cylinder). What is it and how can I fix this problem? From what I've read on ...
5
votes
3answers
15k views

Mass Air Flow Expected Values

I have a 2002 Audi A4 Quattro 3.0. I have a Vagcom USB cable and I am trying to diagnose the MAF sensor. I had a friend get some readings from an OBD2 scanner, which indicated that both precat O2 ...
5
votes
1answer
175 views

Is Torque App reliable to read O2 sensor data?

My 2006 Toyota Prius is throwing code P0420 and I used a cheap OBD-II reader with Torque App on Android to check if my O2 sensors are working or not. I tried the maintenance mode to just run the ...
5
votes
1answer
21k views

P0136 Bank 1 Sensor 2 - Sensor location

I'm getting P0136 bank 1 sensor 2 circuit malfunction from my Toyota Camry 4 cylinder, which from past experience means I need to replace it. I've replaced the O2 sensor in the exhaust manifold ...
5
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4answers
2k views

Can an O2 sensor cause faulty spark plugs on driver side only when the spark plugs were just changed?

I took my truck (2006 chevy silverado 5.3l v8) to chevrolet dealership due to the fact that it kept sputtering then dying. The check engine light was on the whole 9 yards. The fuel pump has been ...
4
votes
2answers
770 views

How to install a California oxygen sensor into a federal catalytic converter assembly?

I have a 2000 Mitsubishi Galant ES 2.4L Engine with California emissions. Installed is a new federal catalytic converter assembly. The problem is that I do not know what kind of oxygen sensor to ...
4
votes
2answers
1k views

How much improvement from replacing an O2 sensor?

I'm currently getting about 19.6 mpg city in my 97 Mazda Lantis 323 / Protege 1.8L. According to fuelly a car like this should be getting around 26 mpg. The car has about 127k miles on it, and I ...
4
votes
1answer
1k views

Subaru Forester OBD Scan Codes “P0130” and “P0130 P”

My 2002 Forester Check Engine light is on. I connected an Autel MaxiScan MS300 OBD-II scan tool and got indication for two codes. Browsing through the codes, it reads P0130 and P0130 P. The first one ...
4
votes
1answer
56 views

1998 Honda Civic - O2 sensor or catalyst failure?

I have the P0420 code on my 1998 Honda Civic DX (catalyst system efficiency below threshold bank 1). I want to be able to properly diagnose the problem myself without just throwing new parts at it. A ...
4
votes
2answers
142 views

What controls O2 sensor/lambda cycling?

I just replaced the lambda on my 98 Mazda 626 GF 2L because it was showing a signal that was constantly pegged lean and I suspected it was defective. After replacing the sensor I took the car for a ...
4
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3answers
106 views

judging oxygen sensor quality

I was looking at oxygen sensors for my vehicle on rock auto and found large price discrepancies. I saw sensors ranging from $25 up to $100. in general what do the more expensive sensors have that the ...
4
votes
1answer
4k views

How long will my motor last having clogged catalytic converters?

My catalytic converters have been clogged for awhile, and the o2 sensors need changed because of this. What is it doing to my engine? And gas mileage for that matter? If i take out my ...
4
votes
1answer
77 views

Exhaust on a replaced motor

I recently had to change the motor in my 2004 Hyundai Sonata. I bought a used one from the junkyard, and it fired right up after I got it put in, and all the wires, hoses, etc. connected. The only ...
4
votes
1answer
445 views

CEL code 43 on 1992 Civic

I'm getting CEL code 43 after doing a lot of work on my car (changing the head gasket, which involved removing and reattaching lots of exhaust and intake components, and replacing the fuel filter and ...
4
votes
1answer
49 views

Does exhaust gas pressure impact the output of narrowband lambdas?

In the course of writing this answer I learnt that the current output of wideband lambda sensors is sensitive to exhaust gas pressure. This technical document for Bosch LSU 4.2 widebands explains how ...
4
votes
1answer
43 views

Why would a lambda sensor fail?

I had an early failure of one of the two lambda sensors in my 2011 Toyota Yaris that was driven for approximately 40 000 - 50 000 km at the time of failure. Fortunately, this was replaced for ...
4
votes
1answer
90 views

Why would one install widebands on vehicles that are setup for narrowbands?

A recent post on one of the forums I frequent has piqued my curiosity. From my limited reading on the topic, widebands do a better job of quantifying air-fuel ratios than their narrowband ...
4
votes
3answers
36k views

How do I resolve error code P1135 in my Toyota Camry?

I recently replaced the downstream O2 sensor in my Toyota Camry. Shortly thereafter, the check engine like came on again providing the following codes: P1135 which I understand to be the upstream ...
4
votes
1answer
56 views

For the love of all things sacred, what technical reason was there for GM to put a different connector on each side for the rear oxygen sensors?

I just busted my knuckles breaking the oxygen sensors free in hopes of swapping them to see if the problem stayed on the driver side or went with the sensor. Only to find out the connectors are ...
4
votes
1answer
151 views

Can I use the same AFR sensor on both banks (bank 1 sensor 1 and bank 2 sensor 1)

Have 1mzfe (skip this paragraph if you don't want backstory) codes p1135/p1130/whatever the ones for the other bank are/ all showed up at the same, perfect time. ie when I was broke. Since then car ...
4
votes
0answers
144 views

My BMW X5 won't stay running

Hello I have a 2003 BMW X5. I just got the engine replace a couple days ago. I went to pick it up but because the shop was done installing the motor but now I have to deal with the other problems I ...
3
votes
2answers
155 views

P1135 code on 2003 Toyota RAV4

I have a Toyota RAV4 2003 and the CEL used to come on and off, but now lately it stay on all the time. I did check with OBD reader and the car had a P1135. I did check the voltage on upstream and ...
3
votes
2answers
60 views

My Toyota fails under full throttle but not when feathered

My car is a Toyota MK4 NA Supra and it has a problem I don't understand. When I push the throttle gently, whether in park or in drive, it gradually builds revs and moves but when I push it hard i.e ...
3
votes
1answer
61 views

Oxygen sensor malfunction

2005 Toyota Tundra v8 This truck overheats with no radiator fluid loss. Also had power loss. Motor shake. Codes came back with a voltage high/low and both oxygen sensors upstream needed replacement. ...
3
votes
2answers
164 views

Where can I buy the 2005 Mazda 3s 2.3L oxygen sensor plug?

I bought an oxygen sensor with the wrong plug. I wonder were could I buy a plug like the one on my car in order to connect the oxygen sensor properly? This is an image of the plug on my car. Does ...
3
votes
1answer
813 views

O2 Sensor Error after replacing spark plugs?

Ford Taurus 2004 Sedan SES DOHC. (The car is actually in the shop right now and I told him to hold off until I get more info.) Took the car to the local shop to get the spark plugs replaced. Because ...
3
votes
1answer
19 views

2000 Honda Accord O2 Heater error

After replacing the O2 sensor due to fault codes 1166 and 1167, I still get 1167-Heater circuit error. I check resistance through O2 sensor heat, about 17 Ohms. Plug has 14 volts feeding heater. I ...
3
votes
1answer
3k views

How do I repair the O2 sensor in a 2001 Toyota Camry?

I have a 2001 Toyota Camry and the O2 sensor near the front of the car is bad (this is confirmed by the code that the computer has returned). Though I'm not particularly knowledgable about cars ...
3
votes
1answer
399 views

Oxygen sensor PID for 2004 Toyota Camry 4-cyl

My 2004 Toyota Camry with 170k miles is pulling a P0420 code, which I've read can be due to a bad catalytic converter or O2 sensors. I have an OBD-II tool with the DashCommand app on my iPhone. ...
3
votes
1answer
310 views

O2 Sensor - 1998 Toyota Camry 2.2L 4-cyl

I was getting a few error messages p1135 being one of them, which seems to indicate that the O2 1st bank 1st sensor should be replaced. My car is 4cyl, so there is only one sensor under the hood (pre ...
2
votes
2answers
43 views

My lambda sensor has a collar around it, I can not see how to unscrew it. (2009 Ford Fusion)

I am looking at the sensor on top of the exhaust with this collar, and I cannot see how to undo it. I cannot see away for a socket will fit? The
2
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3answers
2k views

P0420 in a Prius

EDIT #2: I rescanned, looking at the correct data, and found the rear O2 sensor was definitely bouncing up and down with the forward sensor's lambda reading. Since I have looked for leaks and ...
2
votes
1answer
420 views

Changed O2 Sensor and my mileage went down

I changed the O2 sensor on my 97 Mazda 323 BA 1.8L BP DOCH Lantis and my mileage actually went down. The car had the original sensor in it, with about 200,000 kilometers on it and I replaced it with ...
2
votes
1answer
47 views

Using dry moly lube as an alternative to anti-seize

While shopping for some anti-seize for my O2 sensor install, I came across some transmission lube that had me wondering about whether I could use it as an alternative to anti-seize. It appears to ...
2
votes
1answer
2k views

High short term fuel trim on one side when starting car?

2003 Ford Crown Victoria V8 Engine Dual exhaust 2 cats & O2 sensors per side Since some time last year I've been getting an error code throw up, with seemingly no regularity: P2197 - O2 stuck ...
2
votes
2answers
801 views

Find short circuit in your car

I have three engine code on, two for two O2 sensors and one for EGR Value ($350). My mechanic is suspecting a short somewhere. My O2 sensors give almost 0 home resistance when it should give about 6 ...