P1184

Code

CITROEN P — Powertrain

Vacuum monitoring short circuit to positive

Brand: CITROEN

Type: P — Powertrain

Views: UK: 2 EN: 11 RU: 5

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Page language: EN

Damaged wiring harness (insulation chafed/shorted to battery positive)
Corroded or loose connector pins allowing a positive feed to the signal circuit
Faulty vacuum/pressure sensor with internal short to supply
Aftermarket electrical work or repairs creating a direct short to battery positive
Blown fuse or incorrect fuse routing that applies battery voltage to the sensor line
PCM/input module internal fault or damaged pin shorted to battery rail

Malfunction indicator lamp (MIL) / Check Engine light illuminated
Possible engine running abnormalities (rough idle, hesitation, reduced power) if vacuum feedback used for fuel/air control
Poor fuel economy or rich/lean running depending on system mapping
Stored or intermittent drivability faults under certain conditions
Possible related system warnings if vacuum used by brake assist or turbo control (vehicle dependent)

Read freeze-frame and live data with a scan tool to confirm conditions when DTC set
Verify battery voltage and ground integrity
Visually inspect vacuum sensor connector and wiring along full harness route for damage, pin corrosion, or melted insulation
Backprobe sensor signal, sensor supply (5 V or reference) and ground with ignition ON (engine OFF) and while cranking/running where safe
Check for aftermarket accessories or recent repairs tapping into wiring near the sensor
Inspect fuses and relays associated with sensor power/reference circuits

Expected reference supply: typically 5 V (vehicle dependent)
Expected signal range: typically ~0.5–4.5 V for vacuum/pressure sensors (varies by sensor)
Short-to-positive symptom: signal voltage near reference or battery voltage (≈5 V reference or higher if directly tied to battery)
Short-to-ground symptom (contrast): signal near 0 V

Retrieve full DTC list and freeze-frame data with a scan tool; note conditions (ignition, engine speed, temperature)
Visually inspect sensor, connector and wiring for damage, corrosion or signs of overheating
With ignition ON (engine OFF) backprobe the sensor connector: measure reference voltage, signal voltage and ground. Record values.
If signal reads high (near reference/battery), disconnect the sensor and re-measure the signal at the harness connector with connector disconnected. If voltage falls to expected open-circuit level or 0 V, suspect sensor short.
If harness still shows high voltage with sensor disconnected, trace wiring toward fuse box/PCM looking for short to battery (inspect splice points, relays, accessory taps)
If high voltage disappears when disconnecting PCM harness, suspect PCM or module with internal short — verify grounds and connections then consider module bench test or replacement per manufacturer guidance
If wiring appears intact but intermittent, perform wiggle testing while monitoring live data to reproduce fault
After repairs, clear codes and perform drive cycle to verify DTC does not return

Wiring short to battery (+) between sensor and PCM
Contaminated/corroded connector allowing intermittent high voltage on the signal wire
Failed vacuum sensor (internal short to Vbatt or 5V reference)
Incorrectly installed replacement sensor or harness

⚠️ Status

P1184 — Vacuum monitoring circuit: short to positive detected (signal too high). Inspect sensor, wiring and connectors for short to battery.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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