Throttle position sensors are a key component in any modern engine. If they are giving the wrong reading, everything else goes haywire. Follow this Real Fix to see how a driveability problem on this BMW X5 was diagnosed and repaired.
Vehicle
2001 BMW X5 30i 3.0L
Title
P0101, Replaced Throttle Body
Complaint
The customer states the check engine light is on and vehicle not running right.
Cause
Connected a scan tool and found code P0101 – Mass Or Volume Air Flow “A” Circuit Range/Performance. Performed a road test while monitoring scan tool data and observed the throttle position sensor parameter was not within the specified range. Performed an inspection of the throttle body and detected no signs of deposits or debris. Inspected the throttle position sensor wiring harness and connector, but detected no obvious faults. With the ignition on and the engine off, used a multi-meter to check for the presence of voltage and ground at the throttle position sensor connector and found both were present. Backprobed the throttle position sensor and performed a throttle sweep while monitoring the sensor signal on a lab scope. The throttle position sensor signal observed on the lab scope was above specifications, indicating the throttle position sensor was faulty. The throttle position sensor is integrated into the throttle body and is replaced as an entire unit.
Correction
Replaced the throttle body, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.
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