Question about 1997 Mercury Grand Marquis

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How do you know what O2 sensor is out the code was HO2S21 what does the 2 and the 1 at the end represent

This web site is a waste of my time

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Your better of Googling your questions

Everything you need to know about vehicles
& OBD2 Codes, is all over the internet

Need to study OBD 2 Systems (1996 thru 2013)

Oxygen Sensors

S11 is the passenger side-- on the exhaust
before or in the converter
S12 is the driver side exhaust

Both of those are the front or upstream sensors
that control the fuel trim or injector pulse

If you had a S21 or S22 they would be the sensors in the
converter at the outlet

They are called downstream or Monitors

Those don't do a thing until the converter looses
efficiency,then they watch the switching ratio between
the front & rear, to tell you the converter has failed

HO2 --is Heated Oxygen Sensor

11-front sensor-right side (on a Ford)
12-front sensor-left side
21-rear sensor-right side
22-rear sensor-left side

Not all vehicles are numbered the same as a ford

Posted on Apr 01, 2014


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'08 dodge diesel P0131, replaced both O2's and module. Checked wiring and no problem found

P0131 refers to a problem identified with the upstream O2 sensor. The upstream sensor is the one before the catalytic converter. This code represents a few different possibilities. The possibilities are, as follows: The O2 sensor is dirty, clogged, or defective. That the wiring to the O2 sensor is damaged or shorted. And that the ECU has identified a "Lean" condition. This means that the engine could have an intake air leak and too much non-metered air is going into the engine. The other cause could be a dirty or defective MAF sensor. Diagnostics will be needed to isolate the source, let me know how you make out, good luck.

Dec 10, 2013 | Cars & Trucks

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Always use Google to look up codes
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Jul 21, 2013 | 2002 Toyota Camry

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Check engine light is on and the code is p1133 is this the o2 sensor and how much will his cost me? please help

lmost O2 sensors are less than $75, that code indicates a 'lazy' sensor that is not switching fast enough to satisfy the engine computer-means your engine is probably near 100,000 miles or is in need of routine service (plugs, throttle body cleaning, etc.)-it will run smoother and get better gas mileage if you replace this sensor (bank one, side one, the sensor on the same bank as the #1 cylinder, in front of the catalytic converter).

May 23, 2011 | Chevrolet Tahoe Cars & Trucks

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If I don't drive Acura RSX right away, but idle it for 1 or 2 minutes, then I have engine check with the code P0134 (oxygen A/F heater malfunction). What could it be? Is sensor bad, or just the heater fuse...

99 times out of 100, if the O2 sensor has a heater circuit code, the sensor itself is the problem. The other 1 percent is usually wiring harness problems. Don't waste your time or money on an aftermarket sensor. I don't know exactly why, but every time I tried one, the car would come back in with "Oxygen/ Air Fuel Sensor Lean" codes. Get the sensor from the dealer.

Feb 05, 2011 | Acura RSX Cars & Trucks

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I'm having an OBD error code P1135 on my 2004 Mazda 3. I know the description of the code but it doesn't say how I fix the problem. Some internet searching has hinted at a problem with the Oxygen Sensor...

the code may say o2 sensor out of range, but it doesn't mean the sensor is bad, could be another problem, code readers just give you which sensor read out of range , on a good scan tool you can read all sensor and actuator activity, so lets say o2 is reading high, it could be a missfire in one cyl but not enough to set another code although the o2 sensor will read improper ratio, too many people rely on error codes without checking further therefor wasting money, so get a real scan done by a good tech

Nov 21, 2010 | Mazda MAZDA3 Cars & Trucks

1 Answer

I need to know where the oxygen sensor in a 1992 saturn is located?

Where all O2 Sensors have been for 25 years
In both ends of the converter
Some times, just before converter in exhaust pipe

An O2 Sensor Code---Does Not mean it is bad or has to be replaced
The code indicates it went out of range

You need to find out why.
Then only if you test it, and it has failed,would you replace it.

Oct 07, 2010 | 1992 Saturn SL1

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2004 TOyota Camry LE 2.4 ENgine Code is P2238

P2238 = "O2S 1/1 positive current ckt low"

check O2 sensor for degraded performance or wiring to O2 sensor

Mar 13, 2009 | 2004 Toyota Camry

1 Answer

O2 sensor problem

I have a 97 gmc sierra .This truck is the same as the chevy ok.Its a 350 5.7 liter 4x4 Z71.I took it to auto zone which was my first mistake.They put it the scanner and said bad O2 sensor.Ok so which one is it i said.They dont know.Well there four (4) O2 sensors in this truck i hope you know that.I had to replace all four of them before i had to take it to a real shop.It seems the fuel pump i replaced a week earlier with an auto zone fuel pump was bad.Ive changed my feul pump 4 times now and have 235000 miles on still running.You need to get your fuel pressure checked.It should be 65 psi to start it and 55 psi to run it.If the pressures are good it could be a different O2 sensor or maybe the mass air flow senor.My last option would be the fuel pressure regulator because it seems to be a waste of time and money.I would get that fuel pressue checked first.Good luck.

Oct 30, 2008 | 1997 Chevrolet K1500

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