Tech Tip: BMW Check Engine Light On and Vehicle Running Rough Due to Airflow Meter

Tech Tip: BMW Check Engine Light On and Vehicle Running Rough Due to Airflow Meter

If a customer complains of a check engine light on and a vehicle running rough, it may be due to problems with the airflow meter and wiring.

Vehicle Applications:  

2002 325XI Sport Wagon 2.5L, Eng Des M54; 330XI 3.0L; and X5 3.0L, Eng Cfg L6, Eng Des M54; and 2004 330CI 3.0L and 330I 3.0L

Customer Concern: Check engine light is on and the vehicle is running rough.

Potential Causes: Airflow Meter and Wiring

Tech Tips: Fault code points to airflow meter problems

Diagnostic Codes: P102

Tests/Procedures:

1. At the airflow meter, test for battery voltage on the red/white wire with the ignition on or engine running.

2. Check for ground on the black wire.

3. Test the output signal on the yellow wire. It should be approximately 0.7 to 0.9V at idle.

4. Use a scan tool to monitor the fuel trim numbers and the airflow meter data stream grams/sec readings. Nominal values are 5 grams/sec at idle in Park, and >150 at wide open throttle and 5,000 rpm under load. Some scan tools have a freeze-frame feature, which is useful in troubleshooting if the problem is set at idle versus at cruise.

Courtesy of Identifix, Inc.

You May Also Like

Nissan Vehicle Key Not Detected and Engine Will Not Start

Refer to the service information for complete key system diagnosis and repair information.

Models: All Nissan vehicles equipped with Intelligent Key or Nissan Anti-Theft System (NATS) key. 

Vehicles use radio frequencies (RF) that are similar to other wireless devices. In the event another wireless device is transmitting at the same time as a key, it can interfere with the signals being received by the BCM. If there is interference with Intelligent Key signals, the following symptoms may occur: 

Nissan Electro Hydraulic Steering

Nissan’s steering system is susceptible to driver-error.

Toyota Regenerative Braking System

The brake system of a hybrid may have multiple components to perform regenerative braking and pedal simulation.

Regenerative Braking Service

Regenerative braking takes the forward motion of the vehicle and turns it into electrical energy.

Toyota Prius Battery Codes P0A7F, P2011 and P0A80

A second generation Toyota Prius is at least 12 years old and batteries may need to be replaced. Here’s what the codes mean.

Other Posts

Mercedes-Benz Fuel Pumps

Mercedes-Benz has long been a pioneer of GDI.

Mercedes 4MATIC Diagnostics

The Mercedes-Benz 4MATIC all-wheel drive (AWD) systems have been around for a while now.

Timing BMW VANOS N53 And N54 

To service them, you will need the appropriate toolset to lock the crank and camshaft.

Don’t Miss The April Digital Edition of ShopOwner

The April issue includes technical and management content and is free to download.