The P2187 fault code in your VW Tiguan indicates a system too lean at idle (Bank 1). This means the engine is receiving too much air or not enough fuel in relation to the air, especially when the engine is idling. While a seemingly simple code, diagnosing the root cause can involve several components within your Tiguan’s engine management system. Let’s explore potential issues and troubleshooting steps.
One possible contributor to a lean condition, although less common with a P2187 (which typically points to lean), could be fuel dilution in the oil, potentially stemming from High-Pressure Fuel Pump (HPFP) failures. While HPFP failures often lead to a rich fault, severely fuel-diluted oil can sometimes create scenarios that might indirectly contribute to lean-like symptoms, particularly if the crankcase ventilation system is drawing in and burning this fuel-rich oil mixture. Have you noticed a gasoline smell, especially intermittently? This could be a subtle clue. Checking your oil level is a good first step – an overfilled oil level could suggest fuel dilution.
Another frequent issue in Volkswagen Tiguans, often flagged by a separate code (P2015), is the intake manifold runner position sensor. This system controls airflow into the engine, and malfunctions here can certainly disrupt the air-fuel mixture. VW has revised the intake manifold design multiple times to address durability, and extended warranties sometimes apply to this component. However, you mentioned the intake manifold runner code (and a fuel pressure sensor code) only occurred once. While less frequent codes shouldn’t be immediately dismissed, intermittent issues can be trickier to pinpoint.
To get a clearer picture of what’s happening, measuring the low-pressure fuel system is highly recommended. Connecting a fuel pressure gauge to the low-pressure side can reveal if the fuel supply to the HPFP is inadequate or dropping out, especially when the lean symptoms are present. Low fuel pressure could be a direct cause of a P2187 code.
Furthermore, investigating the in-tank fuel pump and its control module is a worthwhile step. The fuel pump receives power from a control module using Pulse Width Modulation (PWM). It’s been observed that these pumps can spike above 6V initially and then settle below 5V at idle. If the engine is stalling or running lean, monitoring the power to the fuel pump, especially when symptoms arise, might show a complete power drop. A failing fuel pump control module often exhibits temperature-sensitive symptoms. If you suspect this module, a temporary test is to remove it and cool it down (e.g., in a freezer for a short period). If the car runs better when the module is cold, but the issue returns as it warms up, this strongly suggests a faulty fuel pump control module.
By systematically checking these areas – oil condition, fuel pressure (both low and high side if possible), intake manifold runners, and fuel pump module – you’ll be better equipped to diagnose the cause of the P2187 code in your VW Tiguan and take appropriate repair actions.
