Manifold Absolute Pressure Sensor

Replace the Manifold Absolute Pressure (MAP) sensor on the 2005 Mercedes-Benz G500 with 5.0L M113 V8 engine to restore proper intake manifold pressure readings for engine management.

Warnings

Tools required

Parts

• Manifold Absolute Pressure (MAP) sensor × 1 — A0041536728 or equivalent OEM
• O-ring seal for MAP sensor (if not included with sensor) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition off and remove key from ignition
3. Allow engine to cool to ambient temperature (minimum 30 minutes after shutdown)
4. Open hood and secure with prop rod
5. Disconnect negative battery terminal to prevent fault codes during sensor disconnection

Procedure

1. 1

   Locate MAP sensor on intake manifold
   The intake manifold pressure/temperature sensor on the M113 V8 is located on the intake manifold; confirm exact position against Mercedes WIS for engine 113.964 before proceeding. It has one electrical connector — verify the wire count against the vehicle. Identify the correct sensor by consulting the wiring diagram rather than by assumed location, as the M113 uses an HFM (hot-film mass air flow) sensor for primary load sensing.
2. 2

   Disconnect MAP sensor electrical connector
   Press the locking tab on the electrical connector and pull straight away from the MAP sensor. The connector uses a slide-lock mechanism; do not pull on the wiring harness itself. If the connector is tight due to age, gently wiggle while pulling to release. Inspect the connector terminals for corrosion or damage.
3. 3

   Remove vacuum line if equipped
   If the MAP sensor has an external vacuum reference line (hose), carefully pull the hose straight off the sensor nipple. Note the routing of the hose for reinstallation. Inspect the hose for cracks or deterioration; replace if damaged. Some M113 configurations use an integrated sensor without external vacuum line.
4. 4

   Clean area around MAP sensor mounting
   Use compressed air and clean shop towels to remove any dirt, oil, or debris from around the MAP sensor mounting location. This prevents contamination from entering the intake manifold when the sensor is removed. Pay particular attention to the area directly around the sensor body where it meets the manifold.
5. 5

   Remove MAP sensor mounting fasteners
   Remove the sensor retaining fastener(s) — verify exact count and type against Mercedes WIS for engine 113.964, as MB sensors of this era may use a single screw or a retaining clip. Turn counterclockwise to loosen. Keep any fasteners in a clean location for reinstallation.
6. 6

   Extract MAP sensor from intake manifold
   Gently pull the MAP sensor straight out of the intake manifold port. Do not twist or rock the sensor excessively as this can damage the O-ring seal or the manifold port threads. If the sensor is stuck due to carbon buildup or aged O-ring, gently wiggle while pulling. Cover the open manifold port immediately with a clean shop towel to prevent foreign object entry.
7. 7

   Inspect and clean MAP sensor mounting port
   Remove the shop towel briefly and inspect the manifold port for carbon deposits, debris, or damage to the O-ring sealing surface. Use a clean shop towel (never abrasive materials) to wipe the port clean. If using electrical contact cleaner, spray onto a towel first, then wipe the port. Do not spray directly into the manifold. Immediately re-cover the port opening.
8. 8

   Prepare new MAP sensor for installation
   Remove the new MAP sensor from packaging and verify it matches the original sensor design. Install the new O-ring seal onto the sensor body if not pre-installed. Lightly lubricate the O-ring with clean engine oil to ease installation and ensure proper seating. Do not use petroleum-based lubricants other than engine oil.
9. 9

   Install new MAP sensor into manifold
   Remove the shop towel from the manifold port. Carefully align the new MAP sensor with the mounting port and gently press it straight into position until the sensor body seats against the manifold surface. Ensure the sensor orientation allows the electrical connector to face the correct direction for harness connection without strain. Do not force the sensor; it should slide in smoothly if the O-ring is properly lubricated.
   Torque spec

   MAP Sensor Screws3 Nm (2 lb-ft)
10. 10

    Install and torque MAP sensor mounting fasteners
    Install the 2 Torx mounting screws through the sensor bracket (or directly into the sensor if threaded design) and thread them into the manifold by hand until finger-tight. Using a torque wrench, tighten the fastener(s) to the torque specified in Mercedes WIS for engine 113.964 (small sensor screws are typically in the 2.5-4 Nm range); do not overtighten as this can crack the sensor housing or strip the manifold threads. Do not overtighten as this can crack the sensor housing or strip the manifold threads.
    Torque spec

    MAP Sensor Screws3 Nm (2 lb-ft)
11. 11

    Reconnect vacuum line if equipped
    If the MAP sensor uses an external vacuum reference hose, push the hose firmly onto the sensor nipple until it seats completely. Ensure the hose routing matches the original configuration and does not contact hot engine components or moving parts.
12. 12

    Reconnect MAP sensor electrical connector
    Align the electrical connector with the MAP sensor terminals and push straight onto the sensor until the locking tab clicks into place. Gently tug on the connector body (not the wires) to verify it is fully locked. Ensure the wiring harness has adequate slack and is not strained or pinched.
13. 13

    Reconnect battery and clear adaptation values
    Reconnect the negative battery terminal. Start the engine and allow it to idle for 2-3 minutes. After reconnecting the battery, use a Mercedes-capable scan tool (e.g., Star Diagnosis) to clear any stored fault codes and, if required, reset idle/throttle adaptation values; the engine control module will then relearn adaptations during idle. Initial idle may be slightly rough for the first 30-60 seconds as the system adapts.

Reassembly

1. Verify all electrical connectors are fully seated and locked
2. Confirm vacuum line (if equipped) is properly connected and routed
3. Ensure no tools or shop towels were left in the engine compartment
4. Battery negative terminal must be securely tightened

Verification

• Start engine and verify smooth idle with no rough running or hunting
• Check for absence of Check Engine Light on instrument cluster
• Using scan tool, verify MAP sensor is reading manifold pressure correctly (typically 20-30 kPa at idle, atmospheric pressure with key-on engine-off)
• Perform test drive and confirm normal throttle response and acceleration
• Inspect MAP sensor mounting area for any signs of vacuum leaks (listen for hissing) with engine running

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