Important Note – eFlexPro vs eFlexPro2
Please verify whether you have an eFlexPro (Gen 1) or an eFlexPro2 device. This guide applies only to eFlexPro2 systems or newer wiring harnesses.
There may be older videos or instructions online referring to the original eFlexPro (Gen 1) that instruct users to tap into the MAF, MAP, or Throttle Position Sensor using the analog input wire.
⚠️ This is NOT required with the eFlexPro2.
How to identify your device version?
You can confirm whether you have an eFlexPro (Gen 1) or eFlexPro2 in one of the following ways:
- Your order confirmation
- The label on the back of the control unit
- The eFlexApp
If you ordered a Pro kit on or after 05/24/2023, you have an eFlexPro2.
If you have confirmed that you have an eFlexPro2, please continue reading.
What is the white / grey wire used for?
The white / grey wire is an optional 0–5 V analog input, typically used to connect an aftermarket wideband AFR sensor, such as:
- AEM X‑Series
- Ballenger AFR500
- Zeitronix ZT
- Similar wideband controllers
This input is used only for datalogging purposes through eFlexTuner (eflexfuel.com/us/eflextuner)
When connected to an aftermarket wideband, it allows you to:
- Datalog Lambda / AFR values
- Perform open‑loop ethanol fueling adjustments
- Fine‑tune fueling without a dyno
Important technical note
The eFlexPro2 uses a virtual load sensor, therefore:
- No MAF connection required
- No MAP connection required
- No TPS connection required
The white / grey wire has no impact on vehicle operation or system functionality unless it is used for optional datalogging.
Do I need to connect the white / grey wire?
- To run the eFlexPro2 system: ❌ No
- For Closed‑Loop tuning via eFlexTuner: ❌ No
- For Open‑Loop tuning on a dyno via eFlexTuner: ❌ No
- For Open‑Loop tuning without a dyno using an aftermarket wideband: ✅ Yes
Advanced user note
Custom sensor profiles can be created within eFlexTuner to support additional analog sources.
If you require multiple inputs or advanced sensor configurations, please contact us for assistance.
Conclusion
If you do not have an aftermarket wideband, the white/grey 0–5 V analog input wire in the eFlexPro2 harness is typically not connected to anything.
If you do have an aftermarket wideband and plan to perform open‑loop tuning without a dyno, this wire must be connected to your wideband controller.