BMW DTC P120D – Crankcase Ventilation Hose Disconnected / Defective (Bank 1)
DTC P120D meaning on BMW
DTC P120D on a BMW indicates that there is an issue with the crankcase ventilation hose on Bank 1. This hose is responsible for allowing excess gases and pressure to escape from the engine’s crankcase. When this hose is disconnected or defective, it can lead to various problems with the engine’s performance and emissions.
BMW DTC P120D symptoms
Symptoms of DTC P120D on a BMW may include rough idling, decreased engine performance, increased fuel consumption, and potentially a Check Engine Light illuminated on the dashboard. Additionally, there may be visible signs of oil leaks or fumes around the engine compartment.
BMW DTC P120D causes
The most common causes of DTC P120D on a BMW are a disconnected or damaged crankcase ventilation hose on Bank 1. This can occur due to wear and tear over time, improper installation, or exposure to extreme temperatures causing the hose to become brittle and crack.
BMW DTC P120D seriousness
While DTC P120D may not cause immediate engine failure, it is important to address this issue promptly to prevent further damage to the engine and emissions system. Ignoring this fault can lead to decreased engine efficiency and potential long-term damage.
How to diagnose DTC P120D on BMW
To diagnose DTC P120D on a BMW, a mechanic would typically use a diagnostic scanner to retrieve the fault code and perform a visual inspection of the crankcase ventilation hose on Bank 1. They may also conduct a smoke test to check for leaks in the system and ensure proper ventilation.
How to fix DTC P120D on BMW
To fix DTC P120D on a BMW, the crankcase ventilation hose on Bank 1 would need to be inspected for any signs of damage or disconnection. If the hose is damaged, it should be replaced with a new OEM part to ensure proper fit and function. The system should then be tested to verify that the fault has been resolved.
How to erase DTC P120D on BMW
Once the issue with the crankcase ventilation hose on Bank 1 has been fixed, the DTC P120D fault code can be erased using a diagnostic scanner. This will clear the code from the vehicle’s memory and turn off the Check Engine Light on the dashboard.
Recommended tools & DTC Scanners for BMW
Best Diagnostic App for modern BMWs: BimmerLink
Recommended Bluetooth adapter for Bimmerlink: OBDLink CX
Cable adapter for Bimmerlink: Enet Cable USB Type C
For older BMWs we recommend: Autel AutoLink AL319 (2024 version)
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
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