P1392

Code

VOLKSWAGEN P — Powertrain

CMP Sensor Bank 2 Open Circuit Short To B+

Brand: VOLKSWAGEN

Type: P — Powertrain

Views: UK: 42 EN: 91 RU: 56

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or shorted wiring in CMP Bank 2 harness (chafing, pinched, rodent damage)
Corroded, loose, or pushed-out connector at CMP sensor or ECM
Failed CMP (camshaft position) sensor on Bank 2
Short to battery positive (B+) due to contact with power feed or damaged insulation
Open circuit between sensor and ECM (broken wire, connector fault)
Internal ECM fault or damaged ECM pin

Symptoms

Malfunction Indicator Lamp (MIL/CEL) illuminated
Rough idle, misfire, or loss of power
Hard start or no-start conditions (if CMP signal missing)
Reduced fuel economy, limp-home mode on some vehicles
Intermittent stalling or poor drivability

What to check

Read and record freeze-frame and all stored codes with a scan tool; note operating conditions
Visually inspect CMP Bank 2 sensor connector and wiring for damage, corrosion, tucked or pinched wires
With ignition ON (engine OFF) backprobe the CMP connector and measure reference voltage (Vref) and ground
Check for battery voltage on the CMP signal or Vref pin (indicates short to B+)
Measure continuity and resistance between the sensor connector and the ECM pin; check for short to B+ and open circuits
Disconnect CMP sensor and see if the code changes or clears after a drive cycle (helps isolate harness vs sensor)

Signal parameters

Hall-effect CMP: reference (Vref) normally ~5 V (confirm vehicle spec), signal is a square wave toggling ~0–5 V with cam rotation
Variable reluctance (VR) CMP: AC waveform amplitude and frequency vary with rpm (no DC supply required)
If circuit is shorted to B+, expect to read battery voltage (~12 V) on the sensor signal or Vref pins with ignition ON
If open circuit, expect no Vref or no signal at the ECM input; continuity between sensor and ECM will be high/OL

Diagnostic algorithm

Verify customer complaint and record when fault occurs (cold/hot, cranking, running). Scan for related codes (crankshaft sensor, other cam sensors).
Inspect Bank 2 cam sensor connector and wiring for obvious damage, corrosion, or signs of heat/shorting. Repair any visible damage.
With ignition ON (engine OFF) backprobe the CMP Bank 2 connector: check Vref and ground presence. If Vref is battery voltage, suspect short to B+ in harness or wrong supply feeding circuit.
Check voltage at the ECM harness connector for the corresponding pin to confirm whether the fault is at the sensor or upstream at the ECM/harness. Compare readings at both ends.
Measure resistance/continuity between CMP signal and ECM pin. Check for short to battery positive by measuring resistance between signal wire and battery positive; low resistance indicates short.
If no short to B+ is found and wiring checks good, disconnect the sensor and see if code is still present after clearing; if code clears with sensor disconnected and returns with sensor reconnected, replace the sensor.
If wiring is damaged, repair (splice, replace harness section) following solder/seal or OEM repair procedures. If ECM pin is damaged or fault persists after harness repair, consider ECM repair/replacement per manufacturer guidance.
After repair, clear codes, perform functional test or road test and re-scan to confirm the issue is resolved.

Likely causes

Wiring short to B+ at or near the CMP sensor connector (most likely)
Corroded/loose connector causing intermittent contact or high resistance
Failed CMP sensor
Open circuit in harness (broken conductor) between sensor and ECM
Damaged ECM input or internal fault (less common)

Fault status

⚠️ Status

Camshaft Position Sensor (Bank 2) circuit open or shorted to battery positive detected. The ECM sees improper voltage on the CMP Bank 2 input (open circuit or B+ short).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

Repair manuals

Manual library for VOLKSWAGEN

626

Browse 626 VOLKSWAGEN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

VOLKSWAGEN

Your experience will help others

+100 karma for a short comment :)

Was this AI description helpful?

Your feedback helps improve AI descriptions.

👍 Like 0 👎 Dislike 0

Send to email

P1392 — CMP Sensor Bank 2 Open Circuit Short To B+