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Q & A

Q&A - Technical

Q. Will I notice a difference in my vehicle economy if I replace my oxygen sensors?

A. In almost all cases YES. See Why replace oxygen sensors

Q. Will my vehicle performance be improved?

A. In almost all cases YES. Our experience shows oxygen sensor replacement usually has a positive effect on performance. See Why replace oxygen sensors and How often to replace oxygen sensors

Q. Can you tell me if my current sensor is faulty?

A. No. Having experience in Oxygen Sensor diagnosis we know that this requires specialist test equipment and technical knowledge. Vehicle fault diagnosis can be very challenging and the suspect sensor and the vehicle needs to be available for testing. recommends suitably qualified persons always diagnose your vehicle. does not sell sensors for on vehicle testing and we do not offer pre-purchase or drive-in diagnostic services

Q. What is an oxygen sensor, how does it work?

A. See What is an Oxygen sensor?

Q. How do I know if I need to replace my oxygen sensors?

A. See Why replace oxygen sensors

Q. How often do I need to replace my oxygen sensors?

A. We suggest replacement every 80,000km. See How often to replace oxygen sensors

Q. Where are oxygen sensors located?

A. See O2 Sensor Identification and Locations 

Q. How do I change my sensors?

A. See How to Remove and Refit Oxygen Sensors 

Q. Do I need special tools to change my sensors?

A. A special Socket Drive may be required. See How to Remove and Refit Oxygen Sensors or O2Sensors Accessories 

Q. Why does my sensor look different?

A. Some sensors can appear to be a little different, however as long as the application listing details, connector plug and cable length is correct, you should have no problem fitting this sensor 

Q. Why do you say “2 Sensors Required” in many of the application search results?

A. Many vehicles require sensors on both bank 1 and bank 2, so in these cases 2 sensors are required. 

Q. What does “Sensors can vary refer to diagram” mean?

A. Many vehicles have oxygen sensors that have subtle differences. This may vary by VIN number, manufacturing location, month of manufacture or OE supplier at the time. Therefore on some application listings it is important that you COMPARE THE DIAGRAM DETAILS (Connector Plug, Cable Length) with the sensor you are replacing to ensure you are purchasing the correct replacement. 

Q. Will I need to clear any codes from my onboard computer?

A. The short answer is yes but if a faulty sensor is replaced your vehicles onboard computer may recognise the fault has been rectified and turn off the engine check light. This code will still be stored in the historic memory until cleared. 

Q. Do I need a ECM reset after fitting a new oxygen sensor?

A. Fitting a new oxygen sensor, especially an Air Fuel Ratio sensor (AFR) is not always plug and play; some vehicles require an ECM reset. If this is not done correctly the vehicle may perform badly as the ECM has previously learnt to compensate for the fault in the original sensor. The new sensors heater may be damaged by too much current being fed to it by the ECM, trying to compensate for the old sensor. An ECM relearn may take significant time and the sensor may be permanently damaged during this time.

Q. Can I use a universal sensor rather than a direct fit sensor?

A. does not recommend universal sensors, as they do not include the direct fit connector plug. Cable Cutting and Splicing will be necessary for installation and the installer can accidently select the wrong sensor type, as it is impractical to offer a universal sensor for many vehicle applications due to many factors including heater types, ground types and other characteristics. Also, some manufacturers may use white wires for example for the heater and others may use black, thus it is best to use a direct fit connector to avoid confusion. See What is a Direct Fit Oxygen Sensor? 

Q. How do I know my sensor is faulty?

A. Diagnosing sensors faults can vary from very easy (trouble code indicates faulty sensor) through to very difficult (Slight flat spot, poor idle, lower economy, higher emissions). Most vehicles will not suffer o2 sensor problems in the first 80,000km but we have found that if all sensors are replaced at 80,000km you can expect cost effective motoring. 

Q. How many sensors does my vehicle have?

A. Go to application lookup search, enter your vehicle details and a suitable sensors for your vehicle will be listed in the results. Some vehicles have pre and post catalytic converter sensors (upstream and downstream). See O2 Sensor Identification and Locations page. 

Q. What is the difference between a PRE Cat and POST Cat sensor?

A. A Pre cat sensor is positioned in/near the exhaust manifold, before the catalytic converter. A Post Cat sensor is positioned in the exhaust system after the catalytic converter. See O2 Sensor Identification and Locations 

Q. I replaced my sensor and still have a problem!

A. All is not lost and your vehicle should have better performance and be more fuel efficient for replacing your sensor. Vehicle fault diagnosis can be very challenging and that is why recommends suitably qualified persons always diagnose your vehicle. does not sell sensors for on vehicle testing. See Ordering Information page for details. 

Q. Can you recommend someone to diagnose my sensor?

A. Unfortunately this is not feasible as we would have to personally know and recommend from every mechanical repair shop in Australia. We do recommend that suitably qualified persons are used for vehicle and sensor diagnosis, using a suitable diagnostic scanner and have a working knowledge of an automotive oscilloscope.

Q. I cannot find my vehicle listed, can you still help me?

A. Yes, Contact us with your vehicle details as we can supply Oxygen Sensors for most vehicles 

Q. Can I use the original number that is on the sensor (they can usually be found on the body of the sensor) to find a suitable replacement?

A. YES, use our Original Part Lookup search. We have thousands of original numbers cross referenced to sensors and we can cross reference most OE part numbers. If you cannot find your OE number or the specifications vary then Contact us with your vehicle details before you order and we will do our best to find the suitable sensor. 

Q. I have entered my vehicle data or OE number and the diagram displayed does NOT match the sensor I need to replace.

A. ALWAYS COMPARE THE DIAGRAM DETAILS (Connector Plug, Cable Length) with the sensor you are replacing. If there is a mismatch then please Contact us before you order.

At we strive to help you find the correct sensor. We aim to have the most accurate listings possible, including our OE cross references; however we do not warrant that the description or cross references is accurate. If you find any discrepancy please contact us and we will do our best to assist you and to correct any errors or omissions. At our goal is to service you better.

Q. Why is my sensor cheaper or more expensive than other sensors?

A. At we strive to offer quality products from leading brands with savings of up to 50% off retail prices. There are many different types of oxygen sensors and cost of manufacturing and materials does vary. Selected sensors may also fit multiple vehicles allowing us to purchase in bulk. (e.g. your vehicle maybe an Aston Martin and the same sensor may be used on a Ford) 

Q. Why was an incorrect Oxygen Sensor delivered?

A. ALWAYS COMPARE THE DIAGRAM DETAILS (Connector Plug, Cable Length) with the sensor you are replacing. If there is a mismatch then please Contact us before you order.

Several issues may mean your sensor is incorrect, so ensure you enter correct data:

  • You may have searched our database using incorrect data
  • Your vehicle may have had an engine change or upgrade
  • Your sensor may have been previously changed with an incorrect unit.
  • Your sensor has a universal unit cut and joined rather than a direct fit unit.
  • Your vehicle is a non Australian delivered (or grey imported) vehicle.

Q. I have a standard vehicle that originally uses an AFR sensor and I want to replace it because its old, less efficient or just faulty, can you tell me which AFR sensor is suitable?


Q. I have a standard vehicle that does NOT run an AFR sensor can I use an AFR sensor instead of a standard Oxygen sensor?

A. NO. Air Fuel Ratio sensors can look the identical to traditional Oxygen sensors but are NOT interchangeable.

Q. I have an ECU I found on eBay, but it came without a AFR sensor; can you tell me which AFR sensor to use?

A. NO. Any AFR sensor fitted that is not to exact specification will not function correctly and could possible damage your vehicle. More information on non-original applications

Q. I have read up on the web that people make non-original non -specific applications work for them, can you help me?

A. No. The web is full of information and much of it is not verifiable, and quite frankly a lot of information is often useless chatter. The only way anyone can make this work is with the full understanding of how the technology marriage triangle works, or if an aftermarket ECU is purchased from a performance company who supply all the relevant specifications and information. (which they can do because they made the ECU and know exactly what specs are built in and required).


Ordering and Shipping Q&A

Q. How soon after I order my sensor will I receive it?

A. Most orders will be despatched on the same working day (Monday to Friday) if the order is confirmed before 12 midday (Australian Eastern Time) and within 24 hours if order confirmed after midday (Australian Eastern Time) Monday to Friday. For shipping details and estimates see ordering information

Q. Do you have a warehouse I can pick up from?

A. At we have immediate access to a large range of sensors in stock at multiple warehouse locations, ready for rapid shipping; however we DO NOT offer a pickup service. We would generally have over 90% of all our lines in stock at any given time, ready for same day shipping. 

Q. Can I return a sensor for exchange?

A. Yes, but only under certain conditions. You can exchange any new and uninstalled, undamaged product purchased from us so long as it is returned unopened, unused, and with proof of purchase, within 14 days of purchase. See Ordering Information- Returns page for return details. 

Q. The product is not working properly. What do I do?

A. Sometimes the product you receive may have been damaged in transit or is not working properly however this is very rare. If replacing the sensor has not corrected your vehicle performance issue you will need to have the vehicle diagnosed. Vehicle fault diagnosis can be very challenging and that is why recommends suitably qualified persons always diagnose your vehicle. does not sell sensors for on vehicle testing. See Ordering Information page for details.

Q. How long is your product warranty?

A. not only honours, but extends, the manufacturer’s warranty for the products purchased from us. We offer a 15 month (25,000km) product warranty for faulty products due to a material or manufacturing fault arising during the warranty period. See Ordering Information- Warranty page for details 

Q. My sensor arrived with Shipping Damage

A. We always recommend that you inspect your package before you sign for it. Our shipping department makes every effort to prevent shipping damage, but it does happen occasionally. If your merchandise is damaged upon arrival, please keep the original shipping carton and immediately contact Australia Post for a damage report. See Ordering Information- Returns page for return details.

Q. What payment methods does accept?

A. We accept Visa and MasterCard payments through our secure Credit Card payment gateway. We also accept PayPal Express Checkout payments.

Q. Can I use any other payment methods?

A. All our processing and payment systems are automated. This means we are unable to accept cash, telephone, bank transfer or direct deposit payments sorry.

Q. What will show on my credit card statement?

A. When you make a purchase from your credit card statement will show the charge from Engine Sensors (Aust) Pty Ltd


Q. Is Australian GST (Goods and Services Tax) Payable?

A. All prices shown on INCLUDE Australian GST however all export orders for delivery to countries outside of Australia and its Territories will have 10% GST automatically deducted from the item price at the checkout.



Q. Why should I buy sensors from

A. At we have over 25 years automotive experience and have been serving the trade for over 10 years. Our goal is to bring this industry experience combined with leading customer support to you, we are here to help. offer high quality sensors from the leading manufacturers, and back them up with 15 month 25,000km warranty, above the industry standard. We offer a huge range of sensors, for thousands of vehicle applications, with same day despatch on orders confirmed before midday (AET).

Q. Do you only sell Genuine Authentic items?

A. YES, ONLY sells authentic parts from leading manufacturers; we DO NOT sell any products that are NOT AUTHENTIC. We have a very thorough sourcing and quality process and do not consider any items that may potentially be copies or fakes.

Q. Do you have a telephone number I can call you on?

A. No, sorry. No telephone support is offered. Engine Sensors (Aust) is a web based business, however we offer fast and efficient customer service via email. If you haven’t received a reply within 24hrs (business days) then please check your spam or junk folder.





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