P1681

Code

MINI P — Powertrain

Electronic throttle control monitor level 2/3 - engine speed calculation error

Brand: MINI

Type: P — Powertrain

Views: UK: 5 EN: 4 RU: 2

AI status

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Page language: EN

Causes

Faulty or intermittent crankshaft position (CKP) or camshaft position (CMP) sensor signal
Damaged wiring, corroded or loose connectors for speed/position sensors
Noisy or missing reference/ground affecting sensor signals
Faulty throttle control module / electronic throttle body
Engine control module (ECM/PCM) software or internal fault
Battery/charging system voltage issues causing signal errors

Symptoms

Malfunction indicator lamp (MIL/CEL) set
Reduced engine power / limp-home mode
Poor idle, rough running, or stalling
Intermittent loss of throttle response or delayed throttle
Inconsistent or fluctuating tachometer/engine speed display

What to check

Read and record freeze frame and any related/secondary fault codes
Check battery voltage and charging system health
Visually inspect CKP/CMP and throttle wiring and connectors for damage, corrosion, secure pins
Monitor live engine speed (rpm) and compare to raw CKP/CMP signal data if available
Perform wiggle test on wiring while observing RPM and communication data
Check for recent software/TCM/ECU technical service bulletins or updates

Signal parameters

Crank/cam sensor: typical 0–5 V square or sine-type waveform; frequency proportional to engine speed
Hall-effect/VR sensors: ~0–5 V digital pulses (Hall) or AC millivolt waveform (VR) depending on sensor type
Reference supply: sensors commonly use 5 V reference from ECU — check for stable reference
Throttle position: 0.5–4.5 V typical range for TPS; throttle actuator control is via PWM or CAN in some systems
Expected behavior: consistent, noise-free pulses with frequency proportional to RPM; no missing or extra teeth pulses

Diagnostic algorithm

Retrieve all stored codes and freeze-frame data; note related DTCs (crank/cam/throttle/communication).
Clear codes and attempt to re-create the fault; observe whether code returns and under what conditions (crank, idle, load).
Check battery voltage and charging system; ensure stable supply (12.4–14.6 V) during tests.
Visually inspect sensor connectors and wiring harnesses for damage, pin corrosion, or signs of heat/rodent damage.
Using a scan tool, monitor engine speed reported by ECU, raw CKP/CMP counters/lines if available, and compare values in real time while cranking and at idle.
Probe CKP and CMP signals with an oscilloscope (preferred) or high-speed lab scope-capable scanner to verify waveform integrity, amplitude, frequency, and timing. Look for missing pulses, noise, or amplitude dropouts.
Check reference voltage and ground at sensors with key-on and while cranking. Repair poor ground or reference faults.
Perform connector backprobe wiggle tests while monitoring RPM/engine speed data to find intermittent faults.
If sensor waveforms or voltages are out of spec, replace the affected sensor(s) and retest.
If sensors and wiring check good, test or substitute the electronic throttle control module or perform ECU diagnostics per manufacturer procedure. Check for required ECU software updates or calibrations.
After repairs, erase codes, perform throttle adaptation/learn if required by procedure, and road test to confirm fault does not return.

Likely causes

Crankshaft position sensor failure or intermittent signal
Wiring harness connector corrosion or broken conductor on CKP/CMP circuit
Poor ground or low supply voltage to sensor or ECU
Faulty electronic throttle actuator or its internal speed calculation routine
ECU internal fault or need for software update

Fault status

⚠️ Status

Electronic throttle control monitor level 2/3 — engine speed calculation error: ECU detected an inconsistency between calculated engine speed and input speed signals used by the electronic throttle control system.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours

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P1681 — Electronic throttle control monitor level 2/3 - engine speed calculation error