Which EFIE Do I Need?

Before we get into the details, please keep in mind that we recommend the Quad Digital EFIE Basic for about 90% of all vehicles. We recommend this unit for virtually all American cars, all foreign cars older than 1997, and most foreign cars after 1997. In the rest of the article we will cover why, and also the exceptions to the rule.

Quad Digital EFIE Basic

Basic Types of Oxygen Sensor

There are 2 basic kinds of oxygen sensor. They are called "narrow band" and the more modern, and superior, "wide band" oxygen sensor. These are discussed in more detail in Oxygen Sensors, Types of and Wide Band Oxygen Sensors. The most important distinction is whether your oxygen sensors are wide band or narrow band. If you have any doubt about this point, you can contact us and let us look up your vehicle to be sure.

It is often easy to figure out what type of sensors you have. Is your car pre 1997? Then it's narrow band. Is it an American Car? It's narrow band (we've now seen a few wide bands in 2009 American cars, but none before that). If it is a German or Japanese make and was built after 2000, then you should suspect that it has wide band sensors. But here's another test: Does the sensor have more than 4 wires? If it does, then its a wide band sensor. Note that Toyota uses a 4-wire wide band oxygen sensor. All other makes use 5-wire or 6-wire wide band sensors. So if you don't have a Toyota, and your sensor has 4 wires, then it's a narrow band.

Here's another way to tell: Open your hood. Now look up. Do you see a sticker up under the hood with technical data about your vehicle? Often if you have wide band sensors, they are noted on these stickers for the mechanics. Note that it may be called an AFR (Air/Fuel Ratio) sensor, or AFS (Air/Fuel Sensor). These are all synonyms for a wide band oxygen sensor.

One other point: If you have wide band sensors upstream of the catalytic converter, you will still have narrow band sensors downstream. As of this date (2009), we have never seen wide band oxygen sensors being used downstream. I'm sure some day they will start being used, but so far, we haven't seen any.

Number of Sensors

The next point is, "how many sensors do you have?". V-6, V-8 and larger, usually have 2 sensors that are upstream of the catalytic converter, one on each exhaust manifold. Vehicles with 4 cylinder engines usually have 1 upstream sensor. Sometimes you will find some oddball configurations that vary from these.

In the past we have recommended that you treat all of the upstream sensors, but not the downstream sensors. We have since revised that recommendation. We now recommend that you treat all oxygen sensors regardless of whether they are upstream or downstream. Many manufacturers are now using the downstream sensors in their air/fuel calculations, and others are using them to check the function of the upstream sensors, causing odd trouble lights and poor mileage gains. Because this has become so prevalent, we designed the Quad Digital EFIE Basic. It has 4 EFIEs built into one package and makes it economical to treat all of the sensors on your vehicle with one device.

The Quad Digital EFIE Basic has 2 digital EFIEs for treating 2 upstream narrow band oxygen sensors, and 2 analog EFIEs for treating 2 downstream sensors. Using analog EFIEs on the downstream sensors was not a cost saving consideration. We have found that analog EFIEs work better on downstream sensors, while digital EFIEs are clearly superior working on upstream sensors. For more information on why this is so, please see The New Digital EFIE: How It Works.

For those who have wide band sensors, we have created a package where you can get a Dual Wide Band EFIE packaged along with a Dual EFIE Deluxe (a narrow band type) for use on your downstream sensors.

But What About a 4 Cylinder Engine With Only Two Sensors?

If your vehicle uses a narrow band sensor upstream, we still recommend the Quad Digital EFIE Basic. Why? Even though you'll only use one of the two digital EFIEs (for your upstream sensor) and one of the two analog EFIEs (for your downstream sensor), it's still the least expensive way to get both. While it seems pretty wasteful to only use 2 of the 4 EFIEs, it only costs $13 more than the Dual EFIE Deluxe, our dual analog style of EFIE. This also has the most flexibility if you ever need to move your EFIE to another vehicle.

Have Questions? Contact Us

We know it can be a little confusing at times, trying to figure out what device is best for your vehicle. If you would like help with this, you can Contact Us with the information on your vehicle and we will see that you get the product you need. We also have an online Sensor Request Form you can fill out, and we will email you back with the number and type of sensors you have and a recommendation for the EFIE product you'll need. Sometimes its just not clear which EFIE you need from the information you have available. In such cases, let us help you.