Crankshaft Position Sensor Failure

Symptoms

• Engine stalls suddenly and will not restart [1].
• Engine cranks normally but refuses to fire — no injector pulse from the ECM [1].
• Engine warning light may or may not illuminate during or after the failure [1].
• Engine briefly cranks and sputters before dying, especially with an incorrectly sized aftermarket sensor [0].
• Camshaft position sensor fault code (e.g., P0341) may appear alongside a no-start, even when the cam sensor itself is fine [2].

Causes

• Sensor failure due to age, heat cycling, or physical damage — the ECM stops receiving flywheel tooth pulses and cuts injector trigger signals [1].
• Incorrect aftermarket (no-name/Chinese) replacement sensor that is too long, causing it to contact and rub on the flywheel [0].
• Wiring harness connector damage or corrosion at the sensor plug, interrupting the signal to the ECM [1].
• Sensor output voltage that drops below the ~1.5V peak threshold the ECM needs to detect each flywheel tooth pulse [3].

Diagnosis

• Attempt a restart: if the engine cranks freely but will not fire and fuel delivery is confirmed, suspect the crank sensor immediately — the WIS states the ECM will stop triggering injectors if this sensor fails [1].
• Check for fault codes with a scan tool; a crank sensor failure may accompany P0341 (camshaft position sensor range/performance) codes — address the crank sensor first before replacing the cam sensor [2].
• Inspect the sensor tip for physical contact marks or metal debris, which indicate a sensor that is too long and rubbing the flywheel — a common problem with cheap replacements [0].
• With a multimeter or oscilloscope, check the sensor's output voltage while cranking: the signal should peak at least 1.5V for the ECM to detect each flywheel tooth pulse [3].
• Inspect the wiring harness connector at the sensor for corrosion, pushed-back pins, or chafing against nearby components [1].
• If a replacement sensor was recently installed by a previous owner, verify it is the correct OEM-spec length — an oversized sensor will contact the flywheel and cause intermittent or failed operation [0].

Repair

Replacing the crankshaft position sensor on the T1N is a straightforward bolt-out, bolt-in job that most owners can complete roadside with basic tools. The sensor sits opposite the flywheel teeth and is held by a single retaining bolt. The primary risk is using an incorrect-length aftermarket sensor that contacts the flywheel, causing immediate damage and a repeat failure. Sourcing an OEM or verified-fit sensor is essential.

Parts

Plain part names — affiliate links and pricing are coming in a later update.

• Crankshaft position sensor — OEM or verified-fit aftermarket (correct length is critical)

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From the manuals

• Workshop manual (2004–2006)

  "This signal is used by the engine control module (ECM) for detecting ignition TDC of cylinder 1 as the engine rotates. If no signal is supplied by the camshaft position sensor, the vehicle will not start because cylinder order can not be detected. REMOVAL (1) Disconnect negative battery cable. (2) Remove engine cover (3) Disconnect camshaft position sensor electrical connector (Fig. 7). (4) Remove retaining bolt and remove sensor (Fig. 7). INSTALLATION (1) Install camshaft position sensor and tighten bolt (Fig. 8). (2) Reconnect electrical connector (Fig. 8). (3) Install engine cover. (4) Reco"

• Workshop manual (2004–2006)

  "The ECM uses boost pressure combined with intake air temerature to determine the volume of air entering the engine (Fig. 4). DIAGNOSIS AND TESTING- BOOST PRESSURE SENSOR If the boost pressure sensor fails, the ECM records a DTC into memory and continues to operate the engine in one of the three limp-in modes. When the ECM is operating in this mode, a loss of power will be present, as if the turbocharger was not operating. The best method for diagnosing faults with the boost pressure sensor is with the DRB III!scan tool. Refer to the Diesel Powertrain Diagnostic Manual for more information. Ref"

• Workshop manual (2000–2003)

  "OPERATION When the intake manifold pressure is low (high vacuum) sensor voltage output is 0.25-1.8 volts at the ECM. When the intake manifold pressure is high due to turbo boost, sensor voltage output is 2.0-4.7 volts. The sensor receives a 5-volts reference from the ECM. Sensor ground is also provides by the ECM. The ECM uses boost pressure combined with intake air temerature to determine the volume of air entering the engine (Fig. 2). DIAGNOSIS AND TESTING - BOOST PRESSURE SENSOR If the boost pressure sensor fails, the ECM records a DTC into memory and continues to operate the engine in one"

• Workshop manual (2004–2006)

  "40 O2 SENSOR DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 40 OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 43 ACCELERATOR PEDAL POSITION SENSOR DESCRIPTION The accelerator pedal position sensor (Fig. 1) is located on the accelerator pedal assembly. The driver supplies the torque requirements for the engine by operating the accelerator pedal in accordance with the desired speed or acceleration. The pedal sensor converts the mec"

• Mercedes fault-code reference

  "P1617 128 COi [ECM] control unit (A80) Codeword is incorrect or missing. Incorrect COi [ECM] control unit is installed. P1630 016 WSP [SKREEM] immobilizer CANWSP [SKREEM] immobilizer control unit does not answer or is faulty. Bus message error. P1630 032 WSP [SKREEM] immobilizer CANIncorrect authentication value received from WSP [SKREEM] control unit. Bus message error. P1630 064 WSP [SKREEM] Immobilizer CANCDI [ECM] control unit (A80) is faulty. Bus message error. P1661 001 Capacitor voltage 1 Value read too small. Check cables from A80 to injectors. P1661 002 Capacitor voltage 1 Value read"

Sources