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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
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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. ...
10
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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 ...
12
votes
1answer
424 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
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3answers
100k 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
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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?
0
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1answer
66 views

1996 dodge dakota 4 cylinder 5 speed

Bought a new upper o2 sensor but the clip on wiring harness is melted so I want to straightwire them to o2 sensor. Harness wires... black, tan, gray, green with orange stripe Oxygen sensor... black,...
5
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3answers
80k 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 ...
7
votes
1answer
679 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
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 ...
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. ...
4
votes
1answer
6k views

Must the voltage of the post-cat O2 sensor cross 0.5V?

I understand that the voltage on the pre-cat O2 sensor must cross 0.5V (by a 0.3V margin). Is it also the case that the voltage on the post-cat sensor must cross 0.5V? The following image clarifies my ...
4
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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
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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 ...
3
votes
2answers
5k 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 (...
1
vote
3answers
389 views

Is obd code P0133 anything to worry about?

The day before I got this obd code I changed clutch and gear box oil. 15 minutes before I got this code one of my brakes pads completely wore out. I read a bit about the code and I guess they are not ...
0
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2answers
56 views

Can you mix black oil caued by poor air fuel ration with new oi?

Every time I used to drain and add oil it would quickly turn black. That was most probably because i've been driving with a faulty o2 sensor and apparently the air fuel ration due to this is one ...