Pressure Gauges

OneGauge offers compatibility with both analog (1 or 2 wire) or digital (3 wire) pressure sensors. We nearly always recommend users stick with digital sensors rather than analog sensors due to much better accuracy and faster response. Many OEM vehicles only include a pressure switch to trigger a dash ‘idiot light’ and these switches will not provide a true pressure reading, so swapping for a digital sensor is recommended. OneGauge pressure readings can be adjusted to show PSI, bar, kpa, in-Hg, or other units as needed.

Screw terminal A6 can be used as an analog oil pressure input (Standard Motor Products PS60T). OneGauge typically does not recommend these sensors, so by default digital oil pressure sensors are used as the Oil Pressure reading on standard OneGauge screens.

The digital terminals (B1-B7) can all be used as inputs for pressure sensors. We supply Lowdoller brand pressure sensors with our products and recommend them for any pressure sensor needs. These sensors have an incredibly low failure rate and fantastic warranty, plus their pricing is much better than competitive sensors. Sensors with ratings from 15 to 5000+ PSI are available, and please select sensors with a rating 10-20% higher than the maximum pressure you expect the sensor to see.

OneGauge also supports MAP style sensors that will provide both negative (vacuum) and positive (boost) pressure readings.

When data from OBD-II or a Can Bus ECU connection provides pressure data, such as MAP (vac/boost), the associated terminal is switched off by default but could be used to read additional sensors if requested.

• Terminal B1 is designed for use with a 3-Bar, GM Style MAP sensor that provides pressure readings up to 30 PSI as well as vacuum readings.
• Terminal B2, B3, and B4 are programmed for use with 100 PSI digital pressure sensors. Port B2 is designated Fuel Pressure, B3 Oil Pressure, and B4 Additional Pressure 1.
• Terminal B5 is programmed for use with a 200 PSI digital sensor and is designed Additional Pressure 2.

Installing Pressure Sensors

Installation of 3 wire digital sensors is simple- simply wire the red wire to a 5v terminal, black to ground, and green (sometimes yellow) to the signal terminal listed above (for example, Oil pressure is B3). Please note that OneGauge uses digital sensors for standard oil pressure readings- if you’re using a 1-wire analog sensor let us know so we can adjust the code for you.

The pressure sensors we provide are 1/8″ NPT threads by standard. It is usually easy to find adapters for these to fit various engines. Standard NPT adapters (to 1/4″ or 3/8″) are available at many hardware stores. Metric adapters can be found online, including Amazon and Ebay.

Troubleshooting

1. Do you get a pressure reading on the screen (does it change from 0)? If not, unplug the sensor from the black harness and the reading should jump around randomly. If it does not, please contact OneGauge. 

2. Verify that the green wire that provides the sensor signal is connected to the correct screw terminal (for example, B1 for boost, B2 for fuel pressure, B3 for oil pressure). 

2. Take a short piece of wire and connect it between a ground terminal and the terminal for sensor signal in step 2. It should read the minimum for the sensor (usually 0, but in the case of boost it may go negative). Using the same wire, connect the sensor signal terminal in step 2 to a 5v terminal and it should read above the maximum for the sensor (115 PSI for a 100 PSI sensor, for example). Please be careful with this step not to accidentally connect the signal screw terminal to a 12v power source, it will damage the computer. If you get readings not consistent with those mentioned in this step please reach out to OneGauge. 

3. If the gauge constantly reads slightly above the maximum rating for the sensor (115 PSI for a 100 PSI sensor, for example), the black and red power wires are likely reversed. Flip them and check pressure readings. 

4. You can test the harness using a multimeter. Check resistance between each wire and the 3 pins of the harness to make sure that there is little to no resistance between each wire and its corresponding pin. The standard pinout is below though on some harnesses red and black are reversed, so please test appropriately. 

5. At this point, if everything above checks out and the sensor is not working correctly, the most likely culprit is a failure of the sensor itself. If you have another pressure sensor, switch the harnesses to see if the sensor readings work correctly with a different sensor. For example, if you’re having trouble with the boost sensor, use the boost sensor harness on the oil pressure sensor and see if you get reasonable readings on the screen for boost. This will confirm a failed sensor. We strongly recommend the following replacement sensors: https://lowdoller-motorsports.com/collections/pressure-sensors/products/0-100-psi-5v-pressure-sensor

Please be wary of cheap, chinese sensors as we have often found that as many as half of these fail immediately or are already non-functional out of the box.