P1250

What the Code Means

P1250 is a generic code that the scanner maps to a fuel pressure regulator fault. On the M52TUB20 engine (BMW Z3 2.0L), this code doesn't appear in the code list for that engine: the scanner is only guessing which real BMW code the value it read corresponds to, and that guess is not a confirmed definition.

The real code lives in the DME, and you can only get its actual number and description with a scanner running BMW software. One more wrinkle: on this car the fuel pressure regulator sits on the front of the fuel rail, and the DME doesn't monitor rail pressure — so a “fuel pressure regulator fault” as a direct sensor reading isn't physically something the control unit can pick up here.

Symptoms

• P1250 shows up together with a fuel trim fault on both cylinder banks.
• Intermittent misfire that clears up quickly.
• Higher fuel consumption from an over-rich mixture.

Possible causes discussed for this case: a leak in the intake system (vacuum hoses, intake boots) or a clogged fuel filter after the car sat for a long time.

Diagnosis and Repair

Step 1. Pull the Real Code from the DME

Scan the car with BMW software (ISTA, INPA) and get the actual code number and description from the DME. The generic P1250 value is not a reliable definition for the M52TUB20 — build your diagnosis on the real BMW code only.

Step 2. Check the Intake System for Leaks

Inspect the vacuum system and intake boots for cracks and holes; replace damaged hoses. Run an engine smoke test to find leaks in the intake system.

Step 3. Evaluate Fuel Trims

Look at fuel trims in live data with a working scanner — that shows how far the mixture is drifting from spec and whether it's on both banks.

Step 4. Check the Fuel Filter

If the car sat for more than a year, consider checking and replacing the fuel filter: a clogged filter was discussed as a possible cause in this case.