Fuel Pressure Sensor¶
Monitors fuel-rail pressure so the ECU can correct injector flow and decide when closed-loop can be trusted.
What it is¶
The fuel pressure sensor reads the pressure in the fuel rail feeding the injectors. Because injector flow depends on the pressure across them, the ECU needs this reading to know how much fuel a given pulse width actually delivers.
Why it matters¶
Two jobs:
- Injector flow correction — since flow scales with the square root of pressure, the ECU uses the measured pressure to keep its pulse-width math honest as pressure varies.
- Gating closed-loop — if rail pressure drops below what's needed, closed-loop trim is disabled. The ECU won't try to fuel-correct around a hardware fault, and the resulting lean condition is a pressure problem, not a tuning one.
On a diesel, this reading is even more critical: below the common-rail minimum, fuel won't atomize or ignite.
How to tune it¶
It's a monitor, not a setting. Use it diagnostically: a lean condition with injectors not maxed, plus a pressure reading below reference, points squarely at the fuel system rather than the tables.
Watch out
Don't re-tune fuel tables to mask a pressure shortfall. If the sensor shows pressure sagging under load, fix the supply — tables tuned around low pressure will be wrong once it's restored.
In the game¶
The rail-pressure readout appears with the fuel system on the Fuel page. Watch it hold steady under high demand.