P00F9

What it means

P00F9 means the engine control unit has judged the signal from turbocharger outlet pressure sensor A to be out of range or not plausible. The sensor measures charge air pressure on the outlet side of the turbocharger compressor. The code sets when the reading does not agree with other data, such as ambient pressure with the engine off, the manifold pressure sensor, or the boost the engine should be making for its load and speed.

Symptoms

• Engine warning light on
• Reduced power or limp mode
• Poor or uneven boost, or boost that is too high or too low
• Hesitation or flat spot when accelerating under load
• Turbo whistling, hissing or fluttering noises
• Black smoke or poor fuel economy

Possible causes

• Leak or split in the charge air system (hoses, clamps, intercooler, connections) between the turbo and the enginelikely
• Faulty, contaminated or blocked turbocharger outlet pressure sensor or its sensing portlikely
• Damaged wiring, poor connector contact or corrosion in the sensor supply, ground or signal circuitlikely
• Boost control fault such as a sticking wastegate or variable geometry mechanism, or a faulty actuator or control solenoidpossible
• Worn or damaged turbocharger causing real boost pressure to differ from what is expectedpossible
• Fault with a related sensor such as the manifold pressure or ambient pressure sensor, giving a false comparisonpossible
• Fault inside the control unit or an outdated calibration where the manufacturer has published a fixrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting engine speed, load, boost and temperature when the code set; look for other boost, manifold pressure or actuator codes.
2. Visually inspect the sensor, its connector and wiring for chafing, oil, heat damage, corrosion and bent or loose pins.
3. Inspect the charge air pipes, clamps, intercooler and hoses for splits, oil residue, loose joints and signs of leakage.
4. With the ignition on and the engine off, compare the live reading from the sensor with ambient pressure and with the manifold pressure sensor; they should be very close.
5. Check the sensor's reference voltage, ground and signal wiring against the manufacturer's data for that model.
6. Compare outlet pressure with manifold pressure and the requested boost during a road test or loaded run, looking for a sudden drop, spike or slow response.
7. Pressure test or smoke test the charge air system to find leaks that are not visible.
8. Check that the wastegate or variable geometry actuator moves freely and follows commands, and check the turbo for shaft play and damage; the procedure depends on engine and turbo type.

How to fix

• Repair or replace any leaking charge air hose, clamp, pipe or intercooler.
• Clean or replace the turbocharger outlet pressure sensor if it is contaminated or reading incorrectly.
• Repair damaged wiring or connector terminals in the sensor circuit.
• Repair or replace a faulty boost control actuator, solenoid or sticking wastegate or variable geometry mechanism.
• Replace or overhaul the turbocharger if it is worn or damaged, and find out why it failed first (for example oil supply or contamination).
• Update the control unit calibration only if the manufacturer lists an outdated calibration as a known cause for this fault.

Can I keep driving?

Nearby codes

• P00F8GenericTurbocharger Outlet Pressure Sensor A Circuit
• P00FAGenericTurbocharger Outlet Pressure Sensor A Circuit Low