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How do I change the downstream oxygen sensor on a 2004 honda accord

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If this car has heated seats you need to pull out the seat to replace this sensor otherwise you can fish the wire out from beneath the carpet inside the car.

Posted on Jun 27, 2009


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Got Honda accord 2000 code po135 replaced 02 sensor and stil show same code

How to Diagnose a P0135 -Heater
Performance Bank 1 Sensor 1 (GM 3.5L)
January 31, 2012 Updated: October 29, 2014 Written by: Abraham Torres-Arredondo Article Id: 371

image_1.gifIf your check engine light is on and you have a diagnostic trouble code P0135 stored in the PCM's memory... then you've come to the right place to test and troubleshoot the upstream oxygen sensor.
A P0135 DTC says: HO2S Heater Performance Bank 1 Sensor 1... and this means that the PCM (Powertrain Control Module = Fuel Injection Computer) has detected a problem with the front oxygen sensor's heater element or a problem in the heater's circuit (wires).
In this tutorial, I'll show you how to check the oxygen (O2) sensor's heater element and the two circuits that feed it with power (10 to 12 Volts) and ground with a multimeter.
In case you're wondering, where the oxygen (O2) sensor that the code P0135 is accusing of being BAD is... this bad boy is located on the exhaust manifold and before the catalytic converter.
To help you navigate this article, here are its main points:
  1. Symptoms of a BAD Oxygen Sensor Heater Element.
  2. What Tools Do I Need to Test Code P0135?
  3. What Does the Heater Inside the Oxygen Sensor Do?
  4. Circuit Descriptions of the Downstream Oxygen Sensor.
  5. Start Here.
  6. TEST 1: Oxygen Sensor Bank 1 Sensor 1 Test.
  7. TEST 2: Checking 12 Volts to O2 Heater.
  8. TEST 3: Checking the O2 Heater's Ground Circuit.
  9. TEST 4: Ohming the O2 Heater Element.
  10. P0135 O2 Sensor Heater Test Summary.
Buying a Digital Multimeter for Automotive Diagnostic Testing (found at:
  • Scan Tool.
    1. Don't have one?... check out my recommendation: Abe's Scan Tool Recommendation.
  • Wire Piercing Probe.
    1. Although this tool is not an absolute must, if you do buy one, you'll realize just how easy it makes testing the voltages inside the wires.
    2. If you need to see what this tool looks like, you can see it here:Wire Piercing Probe.
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  • Applies To:
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    Buick Vehicles:
    • Rainier 4.2L
      • 2004, 2005
    Chevrolet Vehicles:
    • Colorado 3.5L
      • 2004, 2005
    • Trailblazer
      • 2004, 2005
    3.5L image_thumb_home_page_1.jpg
    How To Test for a Blown Head Gasket (GM 3.5L, 4.2L)
    How to Test the MAF Sensor and Codes: P0100, P0101, P0102, P0103
    How To Test for a Blown Head Gasket (GM 3.5L -FWD)
    All Articles: 3.5L "A day without sunshine is like, you know, night"
    Steve Martin

    Feb 03, 2015 | 2000 Honda Accord

    1 Answer

    My 2002 Honda Accord sputters when idle

    Both codes pertain to A/F ratio sensor 1.

    Jan 09, 2014 | 2002 Honda Accord

    1 Answer

    My check engine light came on. I found out the engine code is P1166 and P1167. Which oxygen sensor do I change, upstream or downstream, or both??

    Start by changine the one closest to the engine. Probably in the exhaust manifold right in the engine bay. Recommend you buy OEM, as I've heard of people having issues with aftermarket sensors.
    There's also a fuse for the heater circuit in the O2 sensors that could be blown, but I'd bet it's just a bad sensor.

    Jan 09, 2014 | 2002 Honda Accord

    1 Answer

    Check engine light on

    Check o2 heater fuse and relay 1st.

    Jan 09, 2014 | 2002 Honda Accord

    1 Answer

    I have a honda accord and I went to Auto Zone and they did a diagnostic check results were P0420 and the following; aa1-A/F ratio concern aa2- air leak near HO2S Heated oxygen sensor aa3- ignition...

    More than likely the catalytic converter has failed. the computer looks at the downstream O2 sensor to determine if the cat is working. If it sees the downstream O2 starting to switch back and forth like the upstream O2 or read consistently higher than it should than it will flag the P0420 code.

    I’m happy to assist further over the phone at

    Aug 31, 2011 | 1999 Honda Accord

    2 Answers

    2004 honda accord v6: check light comes and then goes off. Mechanic did hand held computer scan. code reads p2240 and he says oxygen sensor needs cleaning. Please advise, Harry.

    that code means there is a fault at the bank 2 oxygen sensor.
    as you stand at the frond of the car and look into the engine bay, the sensor is fitted to the middle of the exhaust manifold nearest to you. disconnect the wires on the plug, and i think it is a 22mm spanner or deep socket to remove it.
    there are various proprietary oxygen sensor cleaners on the market, but there is no certainty that this will work. there could be an actual fault with the sensor, or it may be too dirty to clean.

    if finances permit, i would recommending changing the sensor as a matter of course.

    the ecu fault reading can be reset by removing the battery -ve lead for 30 minutes.
    make sure you have the radio code before doing this as you will need to reset this as well.

    if you only clean the sensor and the fault reading comes back, then you will have to change the sensor and reset the ecu again.

    hope this helps.

    Apr 03, 2011 | 2004 Honda Accord

    1 Answer

    I have to replace my O2 sensor on my 1996 Honda Accord LX...Problem is I don't know where it is. This the one I need to replace Oxygen Sensor - OE Type - Exact Fit - Downstream Sensor 4 Wire, Heated. I...

    The oxygen sensor should be in a black box on the intake pipe in the engine bay, its usually a case of just loosening two screws and removing the connection. hope this helps.

    Dec 29, 2009 | 1996 Honda Accord

    1 Answer

    I need the o2 sensor replaced

    On four cylinder models, the upstream oxygen sensor is located at the upper end of the catalyst pipe, right below the exhaust manifold flange (the downstream is located on the catalytic converter itself).
    On four cylinder models, the electrical connector for the upstream oxygen sensor (the one before the catalytic converter) is behind the cylinder head, just to the left of the rear engine mount bracket (or you could find the sensor and simply follow the wire). Depress the release tab and and disconnect it.
    Raise the vehicle.
    Unscrew the sensor (since it has a wire coming from it, and a shield around the place where it goes in, you would be advised to rent a sensor removal wrench from Autozone or one of the same sort).
    Autozone also carries the sensors. They are pretty expensive, something like $60.00, I think.
    Hope this is helpful to you.

    Nov 19, 2009 | 2004 Honda Accord

    1 Answer

    Check engine light

    P0041 Downstream Oxygen Sensors Swapped From Bank To Bank
    How does a P0041 code trigger the check engine light? This code will trigger the light to come on under the following condition:

    The Heated Oxygen Sensor Monitor, a strategy built into the computer, determines if the Heated Oxygen Sensor (HO2S) signal response for a change in fuel trim corresponds to the correct engine bank. If a response from the Oxygen Sensor being tested is not indicated, a trouble code will be set and the MIL (Malfunction Indicator Lamp) will illuminate.
    Possible Causes:
    Crossed Heated Oxygen Sensor harness connectors
    Wiring swapped from one Oxygen Sensor connector to the other
    Wiring changed at the computer connection or in the related harness

    Apr 09, 2009 | 1994 Honda Civic

    1 Answer

    Code P0420

    P0420 Catalyst System Efficiency Below Threshold (Bank 1)

    There is one 02 sensor in front of the catalytic converter (called upstream), and one behind it (downstream). When the engine is warmed up and running normally the upstream oxygen sensor reading fluctuates and the downstream one is fairly steady. In the case where both readings are fairly steady, a P0420 check engine light code is set.

    Possible Causes:
    Oxygen (O2) sensor not working correctly
    Damaged or leaking exhuast (pipe, manifold, catalytic converter)
    Damaged catalytic converter

    Mar 24, 2009 | Chrysler Concorde Cars & Trucks

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