P2173 - Throttle Actuator Control System High Air Flow
The P2173 code indicates that the Engine Control Module (ECM) has detected a higher than expected airflow into the engine while the throttle plate is in a closed or near-closed position. This typically points to an air leak downstream of the throttle body, such as a vacuum leak, or a malfunctioning throttle actuator control system that is allowing excessive air to bypass the throttle plate. The ECM monitors the throttle position sensor and mass airflow sensor to determine if airflow matches the commanded throttle angle. When the discrepancy exceeds a threshold, this code is set.
01. Most Common Causes
- Vacuum leak (cracked hose, intake manifold gasket leak)
- Faulty throttle body (carbon buildup, sticking plate)
- Malfunctioning mass airflow (MAF) sensor
- Wiring or connector issues in throttle actuator control circuit
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Rough idle or high idle speed
- Poor acceleration or hesitation
- Possible stalling
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect vacuum hoses and intake for leaks.
Step 3: Check throttle body for carbon buildup and clean if necessary.
Step 4: Test MAF sensor readings and compare to specifications.
Step 5: Inspect throttle actuator control wiring and connectors for damage.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the issue can cause poor performance, stalling, or reduced fuel economy. Immediate diagnosis is advised.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and simple repairs like cleaning the throttle body or replacing a vacuum hose. More extensive repairs may cost more.