JB4 Fuel Pressure Connector - B58
Current harnesses (excluding B48/58) include this fuel connector already. Older harnesses can purchase the upgrade here. Check your harness before ordering to determine whether or not you have the connector. It's a 3-position connector with black wires that connects to the fuel pressure sensor.
What is the optional fuel pressure harness for (B48/B58)?
This plugs in to the JB4 connector (green wire goes in #21, black wire goes in #4, fuel pressure plug attaches to fuel pressure sensor under engine cover) and allows the JB4 to both datalog high fuel pressure and also offset the fuel pressure signal back to the DME adjusting fuel trims. This sensor DOES NOT increase the DME's internal fuel limit or its tendency to reduce it's boost target as fuel volume increases. It is suggested for correcting fuel trim issues in unique situations like for a larger turbo, heavy E85 mixture experimentation, etc. In most cases there is no benefit to this optional connector.