5. Before the catalytic converter (front/upstream) so it can accurately measure the fuel/air mix in the exhaust coming out of the engine. P0133 is the slow front O2 code. #1 Sensor (Upstream Pre-Kitty) is always the Air/Fuel Sensor and #2 Sensor (Downstream Post-Kitty) is always the Oxygen Sensor. Mine being non-Cali, I bought two sensors, both being Bosch, part numbers 13122 and 15465. The upstream air/fuel sensor has fewer ports for sampling the exhaust and also the shorter wire. Downstream or Upstream O2 Oxygen Sensor for Honda Civic CRV Acura Integra Isuzu. Its job is to monitor the oxygen content exiting the catalytic converter in order to determine if it is operating efficiently. Reduced gas mileage, rough engine idling, and a lit engine indicator are all signs that something is wrong with the sensor. The manual says the rear sensor normally operates in an O2-depleted environment. Downstream O2 sensor: Necessary tools: *12mm wrench *OEM downstream O2 sensor *Anti-seize *PB Blaster (or WD40) *Scissors . 1 to . 4pcs O2 Oxygen Sensor Front Rear Downstream Upstream For Ford Mercury 15717 US. Hereof, what does the downstream oxygen sensor control? About2012 Ford F150 Oxygen Sensor. O2 sensors typically fail because of old age or contamination. As the name suggests, upstream sensors will be located upstream or ahead of, in front of, above, closer to the engine than your catalytic convertors. Click to see full answer. The downstream or after the cat sensors "Cat Monitors" are not really needed unless you want to pass smog. For the price, it was well worth the "hassle". Are o2 sensors interchangeable? Easy to use parts catalog. Although, some vehicle's with inline engines may use more than one upstream O2 sensor. The functionality of the upstream o2 sensor is to monitor the level of pollutants in the engine's exhaust and pass it to the ECU for continual adjustment of the air-fuel ratio. At idle it bounces around .00 and sometimes shows -.00. RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. To perform this test, you need to run your engine at 2,000 RPM and observe your oxygen sensor voltages. . Not saying this is what is going on here. Acuras that are equipped with a four-cylinder engine have two oxygen sensors, an upstream and a downstream sensor. The upstream sensor is located near the exhaust manifold and the downstream sensor on the back exhaust pipe, close to the catalytic converter. The voltage generated from the O2 sensor should be from 0.1V to 0.9V, with 0.9V on the rich side and 0.1V on the lean side. Buy Oxygen O2 Sensor Front Rear Upstream Downstream 15716 15717 15718 15719 Compatible with Ford Jauar Lincoln Mazda Mercury 2 pcs: Oxygen - Amazon.com FREE DELIVERY . Are upstream and downstream O2 sensors interchangeable?, The . Hi there - your understanding and terminology oxygen sensors - "upstream" and "downstream" are correct - upstream is between the engine and (before) the catalytic converter. Front Upstream O2 Oxygen Sensor For Acura Integra Honda CR-V Civic Prelude. This sensor measures the pollutants making it through the converter and out of the tailpipe. The downstream oxygen sensor is located directly after the catalytic converter. If the data between the two sensors becomes more similar, the vehicle's computer may trigger a catalyst . Free shipping Free shipping Free shipping. Later years' sensors are distinctly different. Bank 2 Sensor 2: Front bank downstream; There is only one bank on inline engines, so most of these vehicles will only have a single upstream O2 sensor and a single downstream O2 sensor. **Another confusing part: If you own a non-Cali jeep, buy part number 13122 for upstream!! Save Share. First start is very soon. Denso's description of the two sensors is exactly the same though, at least on the RockAuto web site. A downstream oxygen sensor in or behind the catalytic converter works exactly the same as an upstream O2 sensor in the exhaust manifold. Since oxygen sensor are not cheap and sometimes the PCM (Powertrain Control Module = Fuel Injection Computer) accuses them of being bad when they aren't, testing them (to make sure they're really bad) is a good idea and this article will help you. Only show this user. I understand Rear is Downstream. Upstream or downstream , left or right, doesn't matter, Ford, GM, Dodge, doesn't matter, they are all interchangeable if wire and connector match up. Free shipping Free shipping Free shipping. Join Date: Oct 2011. Choose from our wide range of high-quality O2 sensors manufactured by the most reputable names in the industry. I keep getting annoyed because I find PN's that say they're for upstream and they're for downstream, etc. Please be sure to select the correct Year from .. $13.95. Oxygen Sensor 02 O2 Upstream for Honda Accord CR-V Acura Integra RSX 234-4011. Check engine light codes associated with a bad oxygen sensor. It is what tells your cars ECU when the AFR goes rich, stoic, or lean. Bank 1 Sensor 1 (Upstream) (pre-cat) #2 sensor is less likely to fail than the #1 A/F sensor. The upstream sensor monitors the level of pollutants in the engine's exhaust and sends this information to the ECU that continuously adjusts the air-fuel ratio. The downstream is used to monitor the catalytic converter efficiency. The downstream O2 sensor controls the heat of the catalytic converter. crawl under the Jeep and look straight up past the front driveshaft. Bank 1 is the side of the engine where cylinder #1 is located. 4pcs O2 Oxygen Sensor Front Rear Downstream Upstream For Ford Mercury 11171843. $42.58. Total for this Order: $109.04. it removes the o2 sensor from the exhaust stream so therefore you can have a test pipe installed and it won't pop a CEL for cat inefficacy. Website. the two downstream O2 sensors are after each mini-cat. Your engine's performance depends on the right air-fuel ratio, and the 2012 Ford F150 O2 sensor helps your ECU keep tabs on this ratio so things run smoothly. I would be suspicious enough of a parts website that doesn't have clear language to NOT buy from them. 1. This "efficiency" is typically measured by the difference in the upstream and downstream O2 sensor readouts. The upstream sensor is the one closest to the engine. The high or low voltage signal tells the PCM the fuel mixture is rich or lean. The front O2 does control fuel mix and if it is getting slow you can count on decreased fuel economy. Easy once I got it up on ramps and could get underneath. The upstream sensor is an A/F sensor and its readings look good. $15.16. It is what tells your cars ECU when the AFR goes rich, stoic, or lean. Click to see full answer. Catalytic sensor reads in Volts. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. There are 4 locations for O2 sensors. Trouble replacing upstream O2 sensor. If there's anyone who is kind enough to help point me in the location of where the downstream O2 sensor is, that would be much appreciated. $16.18. The upstream oxygen sensor is situated before the catalytic converter whereas the downstream oxygen sensor is located after the catalytic converter. Replacing the Front O2 Sensor. Shouldn't be this hard just to find the correct sensor, lol. This works great when you're trying to extend the upstream sensor on the stock midpipe for a 2zz swap. Upstream Sensor is in the Exhaust Manifold Pre-Cat. 1 upstream left bank, 1 upstream right bank, 1 downstream. I haven't removed the harness and the whole thing is heat wrapped, so I'm not sure. The two front sensors had been removed and the locations blocked off, and there are two brand new sensors in the rear positions. Downstream Sensor is in the Exhaust Pipe Post-Cat. Depending on your particular Chevy model, both sensors may be disconnected from the engine compartment. Apr 30, 2019. Downstream is after the catalytic converter. It is best to replace O2 sensors in pairs. Why I am asking. Sensor 1 is the sensor closest to the engine. A bad O2 sensor should not affect engine starting, cause a misfire (unless the spark plugs become carbon fouled), or cause engine stalling or hesitation problems. (upstream is wideband, downstream usually is not) 2015 Nissan Murano. Anyway, the upstream O2 sensor is reading in milliamps and not volts. P0141 and P0137 are both rear O2 codes, heater circuit , and low voltage respectively. The post cat (rear) O2 sensor is a tell tale for the emissions inspections. Buy a 2002 Toyota Corolla Oxygen Sensor at discount prices. The downstream o2 sensors are slightly cheaper and comes with a longer harness for custom o2 sensor placements. The upstream sensor is before the catalytic converter, and downstream is after the catalytic converter. If you have a scan tool with you, you may also use it to test the performance of your upstream O2 sensor. Typically, a front (upstream) O2 sensor 1 that is functioning properly will be switching from rich to lean at a fairly steady rate, creating a wavelike formation. Essentially, P0420 means the catalytic converter is operating at a lower efficiency than it is supposed to. 2006 honda accord 2.4l 4cyl engine light on-replaced upstream o2 sensor w/bosch and downstream w/oem dealer /honda o2 sensor-light still on -code says downstream? 2. If you don't need to smog it, just make sure the upstream O2 sensors are in the exhaust before the cat. The downstream o2 sensors are slightly cheaper and comes with a longer harness for custom o2 sensor placements. And of course the upstream sensor is more expensive. This works great when you're trying to extend the upstream sensor on the stock midpipe for a 2zz swap. The sensor number tells us where on the exhaust system, the O2 sensor or the Exhaust temperature sensor is installed. 1 "Bosch 15537 Oxygen Sensor, OE Type Fitment". The 1st sensor is located closest to the engine, and the last is located towards the rear of the exhaust system. sensor 1 is upstream, or before the cats, it could care less what the cats are doing or if they are there. Typically, a front (upstream) O2 sensor 1 that is functioning properly will be switching from rich to lean at a fairly steady rate, creating a wavelike formation. Regular O2 sensors, now called Narrow band, output a voltage of . Buy Now!New O2 Oxygen Sensor from 1AAuto.com http://1aau.to/ia/1AEOS010181A Auto shows you how to remove, install, change or replace an oxygen O2 sensor. It will read very rich almost all the time in around the 0.845v range give or take a little but then if you just let it sit it . The front O2 does control fuel mix and if it is getting slow you can count on decreased fuel economy. $34.85. The snap in tie wrap retainers they include will required me to drill new holes in the bracket that attaches to the coil pack. The post cat (rear) O2 sensor is a tell tale for the emissions inspections. 719. sensor 1 only looks at air fuel ratio. It serves no fuel control purpose. The OBD II system can't evaluate the converter if the upstream and downstream O2 sensors are not functioning normally. Look behind front wheels. It connects to the wiring harness near the cam angle sensor on the back of the motor's head. Upstream, downstream, front , rear. 3 Disconnect the oxygen sensor electrical connector. Part number 13280 O2 sensor is for Cali-emissions and won't fit your upstream. When I am driving it it bounces all around .20, .40. Basically, upstream O2 sensor is usually installed before the catalytic converter (between the manifold and the CAT), while a downstream O2 sensor is installed after the catalytic converter - usually before the muffler. gonefhsn said: The O2 sensors will not swap between up stream an downstream, the plugs are differant, and yes you should have used the blue harness it is the upstream. A/F is 'Air Fuel'. It is always going to be located after the catalytic converter. P0141 and P0137 are both rear O2 codes, heater circuit , and low voltage respectively. Put the rear end of the car on ramps or jackstands . Should I keep the sensors around in order to keep closed loop tune and simply install the downstream sensors with the back out bungs welded in the pipe about 12" downstream of the . Click to see full answer. Upstream vs. downstream. Oxygen O2 Sensor Front Rear Upstream Downstream for Aston Martin Ford Jaguar Lincoln Mazda Mercury Nissan Compatible with Bosch 15717 4.4 out of 5 stars 639 1 offer from $15.99 Your oxygen sensor position can be determined relative to your catalytic convertor. Sensor 2 is the sensor that is located after (downstream) the catalytic converter or also called the post-cat. I couldn't find any diagram or video online for 4th generation odyssey, regarding O2 sensor. Generally, if we are talking about O2 sensors: Sensor 1 = Before Catalytic converter Front (Upstream O2 sensor) Choose top quality brands AC Delco, ACERA, Bosch, DIY Solutions, Delphi, Denso, NGK, NTK, Replacement, Spectra Premium, Standard Motor Products, Walker. Factory replacement Front O2 Sensor (upstream) for ALL VQ37VHR powered Infiniti G37 Coupes and Sedans. Thi. O2 sensors switch between voltages constantly, so the scan tool typically reads . Is Bank One upstream or downstream? Upstream Sensor is in the Exhaust Manifold Pre-Cat. Shop for New Auto Parts at 1AAuto.com http://1aau.to/c/72/4/oxygen-sensorsIn this video, 1A Auto shows you how to identify an upstream or downstream oxygen (. Just saying I'm pretty sure an upstream O2 sensor can also be responsible for a fault code. In case someone searches for this, it appears there's no difference between California and Federal oxygen sensors for the 1zz and 2zz. Easy to use parts catalog. I got the driver side downstream replaced. These senosrs will only fit G37 badged models. Sensor 2 is the downstream oxygen sensor. Unplug the O2 sensor near the back of the motor. I actually described a WIDEBAND sensor. Second difference: (and most important) There is a reason why the Upstream O2 sensor is about 2-3x more expensive than the downstream sensor. Is there a difference between the upstream and downstream O2 sensors? Kind of fiddly, but it will come out. Thinking this was my 420 problem, I bought/installed a new Denso sensor but it still reads the same. You need the front ones for the engine to run correctly. The upstream O2 sensor is typically mounted in your vehicle's exhaust manifold and monitors the air-fuel mixture (ratio of parts air and parts fuel being consumed), while the downstream O2 sensors are used to monitor the performance of your vehicle's catalyst. :thmsup: I work at a Honda dealer and I still have to see a failed #2 Downstream sensor. A "downstream" O2 sensor is placed either in or just behind the converter to monitor oxygen levels after the exhaust has reacted with the catalyst. There are 3 O2 sensors on the chevy vortec V6. The upstream oxygen sensor is placed before the catalytic converter. KAX 234-4587 Oxygen Sensor, Upstream Downstream 250-24253 Heated O2 Sensor Air Fuel Ratio Sensor 1 Sensor 2 Rear Front Original Equipment Replacement set of 2Drilled - Motorbike Rear Sprocket - Titanium Nut - M8 x 1.25 - x6 - Gold Sketch Pad 50# Drawing Paper BTR LS Piston Ring Compressor Tool Kit 3.780-4.030 - LS1 LS2 LS3 L76 L99 LQ4 LQ9 LINFON Newborn Baby Sleep Print Swaddle Blanket Large . The downstream sensor is furthest from the engine. The purpose is to maintain consistent levels of fuel efficiency and cut emissions. A/F and O2 operate differently, so the scan tool must measure/analyze the sensors differently. Asked by Visitor in Hillsboro, OR on January 13, 2021. Testing the oxygen sensor (commonly referred to as O2 sensors) on your Ford 4.6L, 5.4L car (pick up, SUV) is not that hard to do. In case someone searches for this, it appears there's no difference between California and Federal oxygen sensors for the 1zz and 2zz. However O2 sensors are sold as Upstream/Downstream, Left/Right. What does a downstream oxygen sensor do? all the downstream 02 does is compare the numbers given from the upstream 02 and if the numbers aren't different enough, then the ECU knows there is a problem with the cat. The voltage generated from the O2 sensor should be from 0.1V to 0.9V, with 0.9V on the rich side and 0.1V on the lean side. If your O2 sensor is in good condition, it should react to oxygen content and change voltages quickly. Have a Chev 2016 LT / 8L90 installed in a 2008 JK Jeep Wrangler with a Motech of Las Vegas install kit. The ECU mainly uses information from an . KAX 234-4587 Oxygen Sensor, Upstream Downstream 250-24253 Heated O2 Sensor Air Fuel Ratio Sensor 1 Sensor 2 Rear Front Original Equipment Replacement set of 2Drilled - Motorbike Rear Sprocket - Titanium Nut - M8 x 1.25 - x6 - Gold Sketch Pad 50# Drawing Paper BTR LS Piston Ring Compressor Tool Kit 3.780-4.030 - LS1 LS2 LS3 L76 L99 LQ4 LQ9 LINFON Newborn Baby Sleep Print Swaddle Blanket Large . For example, if you replace the downstream left sensor, you should also replace the downstream right. Mar 27, 2011. If this code only applies to the downstream O2 sensor then it will not affect the open/closed loop operation of the engine. Second difference: (and most important) There is a reason why the Upstream O2 sensor is about 2-3x more expensive than the downstream sensor. So any O2 sensor problems have to be dealt with before you can use the OBD II system to diagnose the converter. It's for a 2004 4Runner V6. HELP! Most Toyotas use an A/F sensor as the upstream sensor (before the CAT) and an O2 sensor as the downstream sensor (after the CAT). . Re: O2 Oxygen Sensor - Upstream (front) Amazon. are both downstream o2 sensors the same? An upstream O2 sensor can trip a code as well though. Where as Cali jeeps have four O2 sensors (two upstream and two downstream). However, on most vehicles produced since 1996, replacing one sensor (especially the front engine monitoring sensor) will cause the ECU to set a code for the other sensors. there are 4 total O2 sensors in your Jeep - the two upstream O2 sensors are in the exhaust manifolds (1 in each cast manifold), directly under the intake manifold. I am getting P0420 and I replaced the rear O2, but it might be time to swap the front O2 as well. According to the service manual they also have different jobs. The two upstream sensors are in the left and right exhaust before they join. Bank 2 is opposite to Bank 1. The great news is that here at CarParts.com, we have an oxygen sensor replacement for every application (upstream, downstream, before/after the catalytic converter, etc.). RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. The data from this sensor is compared to that of the upstream sensor. A downstream oxygen sensor in or behind the catalytic converter works exactly the same as an upstream O2 sensor in the exhaust manifold. I am told I need to replace the Bank 1 Rear O2 sensor. Location: Marietta, GA. Posts: 29. Downstream Sensor is in the Exhaust Pipe Post-Cat. Bank 1 Sensor 1. It has a little clip you push in, then pull it out. Buy a 2000 Chevrolet Silverado 1500 Oxygen Sensor at discount prices. It osculates its current usually between -.08 and +.4 at idle and it doesn't really get to crazy but the downstream O2 sensor just seems funny to me. The thing of it is - a P0420 code doesn't necessarily mean you have a problem. It slightly richens the mixture to make the cat heat up faster, and it leans it a bit if the cat gets too hot. $36.68 previous price $36.68 previous price $36.68 + $6.00 shipping + $6.00 shipping + $6.00 shipping. Sensor 2 is the downstream oxygen sensor. Downstream sensor is located at outlet side catalytic converter. Acuras that are equipped with the 3.5L engine have two catalytic converters and four O2 sensors. they are the main sensors that monitor the fuel mixture. ghs57, Oct 8, 2016. I found the upstream O2 sensor, in the front of the engine, but I'm not too sure on where the downstream one is. The upstream sensor is used by the PCM to control the A/F ratio. Jun 5, 2010. The way you determine whether or not an O2 sensor is upstream or downstream is all done visually. Is sensor 2 upstream or downstream? I do appreciate your feedback on upstream O2 voltage, thanks! Oct 18, 2007. Think of it as . I need some serious help on how I can replace the driver side upstream O2 sensor (the one near the engine). Easy to use parts catalog. SW, Michigan. If it's not getting a proper reading (to set that baseline) the downstream will pick up too much difference and trip the code. It is the sensor that measures the oxygen content in the exhaust, providing an input to the computer, which determines how to adjust the air/fuel ratio. Knowing the location of the oxygen sensor at fault is important. It's whatever's stock for the '11. it refers to the location of the oxygen (o2) sensors relative to the engine. I want to disable the downstream O2 sensors and not install CATs. The sensor produces a voltage that changes when the amount of unburned oxygen in the exhaust changes. Locate the downstream O2 sensor; it is in rear-half the catalytic converter, on the driver's side (middle of the car is where you should be looking) 3. The first step is to unplug the O2 sensor. P0133 is the slow front O2 code. 9 volts, depending on Oxygen levels in exhaust. (in some rare cases weird flow downstream that causes turbulence or backpressure can cause problems but not usually) Sensor 2 is downstream or after the cats, their sole purpose is to make sure the . Which O2 sensor goes bad first upstream or downstream? When I got my car it already had a catless X-pipe installed. Sensor 1 = located before the Catalytic Converter Front (Upstream O2 sensor) Sensor 2 = located after the Catalytic Converter Rear (Downstream O2 sensor) In the case of more than 2 sensors, such as in diesel engines as they need a lot of exhaust temperature sensors, there might be sensor 1-2-3-4 etc. Sensor 1 is the upstream oxygen sensor. my mechanic says drive car for awhile . New to the forum. 4. The downstream sensor is a heated oxygen sensor and reads the emissions after the catalytic converter. It serves no fuel control purpose. The first sensor is before the catalytic converter. . The upstream oxygen sensor is situated before the catalytic converter whereas the downstream oxygen sensor is located after the catalytic converter. Some use AKA slang to distinguish the front (A/F) and rear (O2 only) so they use "Air Fuel Sensor". RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Choose top quality brands Bosch, DIY Solutions, Delphi, Denso, NGK, Replacement, Spectra Premium, Walker, Walker Products. The "upstream" O2 sensor(s) in the exhaust manifold (s) monitor the air/fuel mixture, while the "downstream" O2 sensor(s) to monitor the catalytic converter (s). The measurement is based on oxygen, so its called an 02 sensor. Only show this user.