Code
DF998
RENAULT
D
-> P0471 - turbine inlet pressure
Views:
UK: 4
EN: 8
RU: 6
AI status
Completed
Completed
100%
Causes
- Faulty turbine inlet / exhaust pressure sensor
- Damaged, corroded or disconnected wiring/connector to the sensor
- Exhaust restriction (clogged DPF, restricted manifold)
- Turbocharger actuator/wastegate stuck or turbo mechanical fault
- Boost control solenoid or vacuum supply fault
- Intake or intercooler leak causing incorrect pressure readings
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine power or limp-home mode
- Poor or erratic turbo boost response (low or excessive boost)
- Black smoke from exhaust under load
- Unusual turbo noises or whistle
- Higher fuel consumption or rough running
What to check
- Scan ECU and record freeze-frame data and all stored DTCs
- Monitor live data: turbine inlet/exhaust pressure, boost, MAP, wastegate position, commanded vs actual turbo actuator
- Visually inspect sensor connector and wiring for damage, corrosion, or disconnection
- Inspect exhaust path for restrictions (DPF, catalytic converter, manifold)
- Inspect turbocharger, actuator, and wastegate for free movement and correct operation
- Pressurize intake/intercooler and check for boost leaks (smoke test)
Signal parameters
- Sensor typically uses a 5 V reference and ground; signal output is proportional to pressure (back-probe expected signal roughly 0.1–4.9 V depending on pressure)
- Refer to OEM conversion table for exact kPa/bar-to-voltage scaling for this sensor
- At key-on and engine off: check for correct reference voltage (~5 V) and a stable ground
Diagnostic algorithm
- Retrieve DF998/P0471 and related codes; note freeze-frame data and conditions when code set.
- Visually inspect sensor, wiring harness and connector for damage, corrosion or water ingress; repair as needed.
- With ignition on, back-probe sensor: confirm 5 V reference, good ground, and that signal voltage is within expected idle/atmospheric range. If reference or ground missing, trace wiring to ECU.
- With engine running, monitor live sensor signal while inducing known pressure changes (hand pump or controlled boost) or during road test; verify signal changes proportionally and matches commanded boost. If signal does not change, suspect sensor or wiring.
- Inspect and test turbo actuator/wastegate and boost control solenoid for correct operation; replace or repair if mechanically stuck or electrically faulty.
- Check for exhaust restrictions (DPF, cat, manifold) that could elevate turbine inlet pressure and cause out-of-range readings; clean or replace as required.
- Pressure/leak test intake and intercooler plumbing (smoke test) to rule out leaks that distort pressure readings.
- If wiring and mechanical systems check OK, bench-test or replace the turbine inlet/exhaust pressure sensor. After repair, clear codes and perform test drive to confirm repair.
- If code persists after sensor replacement and wiring checks, consider ECU-related faults and consult OEM procedures.
Likely causes
- Sensor failure or internal short
- Connector corrosion or poor pin contact
- Blocked/partially blocked DPF or exhaust manifold increasing backpressure
- Stuck turbo vane/wastegate or failed actuator
- Leaking or disconnected boost/vacuum hoses or intercooler joints
- Failed boost control solenoid
Fault status
Status
Turbine inlet pressure sensor/circuit — range/performance fault
Repair difficulty: Medium
Diagnostic time: 1-4 hours
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