Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [o2-sensor]

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.

14
votes
1answer
65k 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. ...
13
votes
2answers
7k 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 ...
12
votes
4answers
1k 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 ...
12
votes
1answer
429 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
2k 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
votes
3answers
101k 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 ...
10
votes
1answer
2k 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 ...
10
votes
2answers
2k views

What can cause slow oxygen sensor readings?

I have very slow primary (pre-cat) oxygen sensor readings on my 02' Corolla (2ZZ-GE, 141kW N/A). While trying to investigate the issue, I repeated diagnostics frequently. Before every diagnostic ...
9
votes
4answers
30k 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: http://www.amazon.com/review/...
9
votes
3answers
55k 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 ...
8
votes
3answers
6k views

Shouldn't my post-cat O2 sensors (lambda probes) be reporting varying numbers?

On my 2002 BMW E46 330Ci, I've been getting error codes 202 Lambda regulating limit Bank1 and 203 Lambda regulating limit Bank2. Here's the angry sensor readings from the INPA software: I understand ...
8
votes
1answer
349 views

Changing from two heated O2 sensors to a single O2 sensor

I'm going to be removing a Motorcraft 2150 carburetor in a 2.8L V6 and swapping it for a Ford CFI (and ECU) from a 3.8L V6. I've just recently pulled everything (ECU, throttle body, sensors, harnesses,...
8
votes
2answers
4k views

Can a check engine light reset itself when a scan tool is connected?

I have a Toyota RAV4 2002 4WD. I was driving to the car wash when suddenly the check engine light come on when I accelerated hard. After the wash, it still was on. I drove home, shut it off, turn it ...
7
votes
3answers
1k 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
votes
1answer
684 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. ...
7
votes
4answers
184k 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 ...
7
votes
1answer
13k 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 ...
6
votes
2answers
13k 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
1k 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
3answers
3k views

Removing stubborn o2 sensor - danger of stripping thread?

(2002 Toyota Previa/Estima/Tarago ACR30, engine 2AZ-FE) One of my two pre-cat O2 sensors is faulty. The garage I put the car in did not manage to replace it - they told me it is stubborn and that ...
6
votes
3answers
6k views

Driving without oxygen sensor

I am getting my oxygen sensor replaced today and the mechanic gave the car back so I could do errands while the part is being delivered, which will take several hours. In the meantime, the car's ...
6
votes
1answer
579 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
6k views

Identifying faulty O2 sensor with scan tool

I have a 2002 Toyota Corolla (engine 1zz-de) and I am trying to get to the bottom of a p0171 code. I've read from other posts that a faulty O2 sensor could cause the lean condition, so I have been ...
6
votes
1answer
4k 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 ...
6
votes
2answers
80 views

Does the computer oscilate engine power

A few days ago I started to research auto repair and started with the engine (as you do). I have a question about the engine power and the relation to upstream O2 sensor. If I understand things ...
6
votes
1answer
96 views

O2 sensor replacement

I'm leaving on a 800 mile trip tomorrow and check engine light came on. Took it to autozone and computer said it was the o2 sensor. Is this something that should be replaced prior to the trip or can ...
5
votes
2answers
20k 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 don'...
5
votes
1answer
2k 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 ...
5
votes
4answers
6k 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 ...
5
votes
1answer
625 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 ...
5
votes
1answer
50k 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
votes
3answers
81k 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 ...
5
votes
1answer
3k views

02 sensor displays constant 3.3 volts, not a jagged waveform. 2002 rav4

Got P0420 and P0430 codes, suggesting the catalytic converter needs to be replaced. Everything I have read suggests the wave form after the cat ( sensor 2) should be a delayed version of before the ...
5
votes
1answer
3k 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. ...
5
votes
1answer
64 views

Engine lean issues

Vehicle is a 2006 Ford Courier, started having hesitation/loss of power after fill up at a gas station that I'd never been to before. I depend on it for transport so I'm forced to still drive it, ...
5
votes
5answers
87 views

What causes narrowband O2 sensor behaviour?

It's a given that narrowband O2 sensor (Lambda) output swings up and down within the 0-0.9v range, but everywhere (on the 'net including here) I am seeing people say this is due to the ECU in closed ...
5
votes
2answers
91 views

Is there a chemical limitation to the mixture an engine can maintain?

I know that the question/title is a bit ambiguous, but I couldn't wrap it in a single sentence, so please let me elaborate. You can change the mixture of an engine for whatever reason. Because of ...
5
votes
1answer
72 views

New to mechanical work. Is this a safe way to clean oxygen sensor, or any similar part

https://www.youtube.com/watch?v=tD9KXAukO9M So I found this video of a guy cleaning their oxygen sensor out with an ultrasound cleaner. I presume what it is doing is breaking up the carbon build up ...
5
votes
1answer
2k views

How could the code point to a faulty cat, when the O2 signals are normal?

I'm getting code P0420 on an '03 Vibe. The rule of thumb is that this means the catalytic converter is gone. Yet the pre- and post- cat O2 signals appear to indicate that the cat is doing its job. ...
5
votes
1answer
918 views

Replaced catalytic converter, O2 sensor went out, Replaced it and check engine light is still on

About a month ago I replaced my catalytic converter, a few weeks later the O2 sensor went out. I replaced that too and I'm still getting a check engine light code for the same sensor. What else should ...
5
votes
5answers
14k 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
4k 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
1answer
2k 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
2answers
2k views

Trouble rewiring O2 sensor harness after dogs ate it

This is a 2005 GMC Yukon 4x4 4.8 L. Ok, dogs actually ate my harness going to Bank 2 Sensor 1 O2 sensor. The connector from the body side of the wiring is completely gone. I found a connector I can ...
4
votes
2answers
8k views

Is the after catalyst oxygen sensor used for engine mixture control?

People have often stated that the oxygen sensor installed behind the catalytic converter in a common gasoline engine setup has only one function: to test the health of the catalytic converter. ...
4
votes
1answer
3k 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 ...
4
votes
2answers
2k 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
votes
1answer
103 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
928 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
434 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 warranty....