P0193 — Fuel Rail Pressure Sensor Circuit High Input
P0193 sets when the FRP sensor signal voltage is above the calibrated maximum, typically an open circuit or short to power. A full 5 V signal almost always indicates an open circuit or failed sensor. Disconnect and continuity tests isolate wiring vs sensor before parts replacement.
Fault Overview
Open signal wire, short to power, failed sensor with internal open, poor connector contact, and damaged harness are the primary causes. Check for pulled pins or corrosion before replacing the sensor. On some trucks the sensor is part of a higher-cost assembly — confirm before ordering.
Engine & Platform Coverage
Symptoms
- •P0193
- •FRP sensor high voltage
- •fuel rail pressure circuit high
- •P0193 open circuit
Possible Causes
- 1.Open signal wire
- 2.Short to power
- 3.Failed sensor (internal open)
- 4.Poor connector contact
- 5.Damaged harness
Wiring & Circuit Notes
Inspect connector pins, signal wire for open or short to voltage, and 5 V reference integrity.
DVOM Specs & Sensor Tests
Signal voltage at or near 5 V with open circuit. Disconnect test: observe pull-up behavior. Continuity from ECM to sensor.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
5 steps locked behind Technician Mode- 1Step 1 — Measure Signal Voltage KOEO: Measure FRP sensor signal voltage at key-on engine off. A reading at or near 5 V confirms the circuit is open or the sensor has failed internally.
- 2Step 2 — Disconnect Sensor and Recheck Voltage: Disconnect the sensor and recheck the signal voltage at the harness connector. If voltage drops significantly, the sensor is pulling the circuit high.
- 3Step 3 — Check 5 V Reference and Ground: Verify the 5 V reference and ground are present and within specification.
- 4Step 4 — Continuity and Short Tests on Signal Wire: Perform continuity and short-to-power tests on the signal wire from the ECM to the sensor connector.
- 5Step 5 — Inspect Connector Carefully: Inspect the connector for pulled pins, corrosion, or oil intrusion.
- 6Step 6 — Replace Sensor if Circuit Is Good: Replace the FRP sensor if the circuit is proven good and the voltage remains high with the sensor disconnected.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Repair open wiring $80–250; clean or replace connector $50–150; replace FRP sensor $80–350.
Start Diagnosing This Fault Now
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Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.