What are the common causes of the P0112 code on a Mercedes-benz?

cause_iat_sensor, cause_wiring_damage, cause_connector_corrosion

How much does it cost to fix the P0112 code?

The estimated repair cost for the P0112 code is $50 - $200. This includes parts and labor.

P0112Mercedes-benz GlcYıllar: 1996 - 2026

Intake Air Temperature (IAT) Circuit Low Input

ASE Sertifikalı Teknisyen Tarafından İncelenmiştir

Araç Sürülür Mü?Driving with a P0112 code is generally safe for short distances, but prolonged operation can lead to issues. The PCM uses IAT data to calculate fuel delivery and ignition timing. An incorrect, consistently high-temperature reading (due to low voltage) will cause the PCM to lean out the fuel mixture and retard timing. This can result in reduced engine performance, increased fuel consumption, rough idle, and potentially engine knocking or pre-ignition under load. Over time, a consistently lean condition can lead to catalytic converter damage or other engine component wear due to excessive heat.

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Bu ne anlama geliyor?

Code P0112 indicates the IAT sensor is sending an abnormally low voltage signal (indicating high temperature) to the PCM.

Yasal Uyarı: Bu arıza kodu standart OBD2 sisteminin bir parçasıdır ve 1996-2026 yılları arasında üretilen Mercedes-benz Glc modelleri için geçerli olabilir. Ancak bu spesifik kodun varlığı, aracınızın tam motor konfigürasyonuna ve üretim yılına bağlıdır.

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Yaygın Nedenler

Arızalı Emme Havası Sıcaklığı (IAT) sensörü

Hasarlı, aşınmış veya kopuk kablo tesisatı

Korozyona uğramış veya gevşek elektrik konnektörü

Dikkat Edilmesi Gereken Belirtiler

Motor Arıza Lambası yanar
Yakıt tüketiminde artış
Düzensiz veya dengesiz rölanti

Nasıl Teşhis Edilir

Perform a thorough visual inspection of the Intake Air Temperature (IAT) sensor and its wiring harness. Look for any signs of physical damage to the sensor itself, such as cracks or corrosion. Carefully inspect the electrical connector for bent pins, corrosion, or a loose fit. Trace the wiring harness from the IAT sensor back to the Powertrain Control Module (PCM), paying close attention to areas where the harness might be chafed, pinched, or melted, especially near hot engine components or sharp edges. Rodent damage is also a common culprit for wiring issues.

With the ignition OFF, disconnect the IAT sensor connector. Using a digital multimeter, measure the resistance across the two terminals of the IAT sensor itself. Compare this reading to the manufacturer's specifications for the ambient air temperature. A typical IAT sensor is a Negative Temperature Coefficient (NTC) thermistor, meaning its resistance should decrease as temperature increases. If the sensor shows an extremely low resistance (near zero ohms) even when cold, or if it shows an open circuit (infinite resistance), the sensor is likely faulty. You can also gently warm the sensor with a heat gun (carefully, not excessively) and observe if the resistance drops smoothly; a healthy sensor will show a clear, consistent change.

With the IAT sensor disconnected and the ignition ON (engine OFF), use a multimeter to back-probe the IAT sensor connector. One terminal should show approximately 5 volts (V) from the PCM (this is the reference voltage). The other terminal should show a good ground connection (near 0V or continuity to chassis ground). If the 5V reference is missing, check for an open circuit in the reference wire back to the PCM. If the ground is missing, check for an open circuit in the ground wire. If both are present, reconnect the sensor. If the P0112 code persists, disconnect the PCM connector and the IAT sensor connector, then check for continuity between the IAT signal wire and chassis ground. Any continuity indicates a short to ground in the wiring harness, which would pull the signal voltage low.

Connect a scan tool capable of displaying live data. Monitor the Intake Air Temperature (IAT) sensor reading. If the code P0112 is active, the scan tool will likely display an extremely high temperature reading (e.g., 250°F / 120°C or higher, depending on the vehicle's default for a low voltage input). Compare this reading to the actual ambient air temperature (if the engine is cold) or the Engine Coolant Temperature (ECT) sensor reading (if the engine is at operating temperature). Disconnect the IAT sensor while monitoring live data; a healthy circuit should typically cause the IAT reading to drop to a very low temperature (e.g., -40°F / -40°C) as the PCM interprets an open circuit as maximum resistance/minimum temperature. If disconnecting the sensor does not change the reading from the high temperature, it strongly suggests a short to ground in the wiring harness or a faulty PCM input.

Sık Görülen Çözümler

Replace the Intake Air Temperature (IAT) sensor: This is the most frequent solution if the sensor itself is internally shorted, providing incorrect resistance readings, or has failed internally.

Repair or replace damaged wiring or connector: If diagnostic steps reveal a short to ground, an open circuit, or corrosion/damage within the IAT sensor's wiring harness or connector, repairing the specific section or replacing the entire connector/harness segment is necessary.

Address a short to ground in the IAT signal circuit: If the wiring tests indicate the signal wire is shorted to ground, locate and repair the short. This often involves tracing the harness carefully for chafing or damage.

Replace the Powertrain Control Module (PCM): In rare instances, if all sensor and wiring tests confirm integrity, the internal IAT circuit within the PCM itself may be faulty. This should only be considered as a last resort after exhaustive testing of the sensor and wiring.

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Tahmini Tamir Maliyeti

$50 - $200

Parça$15 - $150

İşçilik$100 - $450

Tamir Zorluğu

Kolay

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Intake Air Temperature (IAT) Circuit Low Input

ASE Sertifikalı Teknisyen Tarafından İncelenmiştir

Bu ne anlama geliyor?

Code P0112 indicates the IAT sensor is sending an abnormally low voltage signal (indicating high temperature) to the PCM.

Nasıl Teşhis Edilir

Sık Görülen Çözümler

Replace the Intake Air Temperature (IAT) sensor: This is the most frequent solution if the sensor itself is internally shorted, providing incorrect resistance readings, or has failed internally.

Bu ne anlama geliyor?

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Dikkat Edilmesi Gereken Belirtiler

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Diğer Popüler Mercedes-benz Kodları

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Diğer Popüler Mercedes-benz Kodları