Fix P2173: Mechanic’s solutions that WORKED

The code P2173: High Airflow/Vacuum Leak Detected (Slow Accumulation) indicates a fault in the Throttle Actuator Control System, usually suggesting high airflow or a vacuum leak. It’s commonly associated with various throttle body or intake system issues, including electrical and mechanical faults. The code signals that the engine is detecting more air entering the system than is expected, leading to potential performance issues.

P2173 quick overview

Meaning	P2173: High Airflow/Vacuum Leak Detected (Slow Accumulation)
Is it serious?	Yes, it is serious as it can affect the vehicle’s performance and fuel efficiency.
Possible causes	– Faulty Throttle Actuator Control (TAC) module – Open or shorted Throttle Actuator Control (TAC) module harness – Poor electrical connection in the Throttle Actuator Control (TAC) module circuit – Throttle plate sticking due to carbon build-up – Faulty Engine Control Module (ECM)
How to diagnose?	Check Possible Causes: Refer to the list of possible causes for initial guidance​ ​Visually Inspect: Look at the wiring harness and connectors for any damage or corrosion​ ​Check for Damage: Look for damaged components, broken, bent, pushed out, or corroded connector pins​ ​Ensure Connections: Confirm that all the connections are secure and tight

How to fix P2173 – learn from mechanics

I looked into P2173 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Hyundai

Vehicle Information:
2006 Hyundai Sonata GLS 3.3L – Experiencing surge and stall.

Issue + Repair History:

• The car was a repossession with no available history.
• It starts and idles with surges, then stalls, showing limited throttle response.
• Sets 3 consistent codes. Reflash and new throttle body didn’t resolve the issue.
• P2173 indicated high airflow; a new MAF sensor was tried without success.
• Found vacuum leak at the back of the engine due to valve cover gaskets leaking oil and causing a small fire.
• Damage included a melted hole in the bottom of the plenum and burn marks on the throttle body.

Other OBD2 Codes + Test Results:

• P1295: Limp home mode-power management.
• P2106: Limp home mode-force limited power.
• P2173: Throttle actuator control system-high air flow detected.

Suggestions to Fix Issue:

• Check for vacuum leaks at the intake manifold gasket.
• Inspect the intake gaskets, power brake booster, and fuel tank evap system for leaks.
• Post data that the PCM is seeing to identify the root cause.
• Consider faulty MAP or Throttle Position Sensors and check their circuits.
• Conduct a volumetric efficiency test on the MAF sensor.
• Reflect on fuel trims if a vacuum leak is suspected.

Final Fix:
Unplugging the MAF and MAP sensors allowed the engine to run long enough to detect a vacuum leak at the back of the engine. Repairing the damage from the oil leak and the small fire, including replacing the valve cover gaskets, throttle body, and plenum, resolved the issue. The P2173 code, initially leading to a focus on the throttle body and reflash, was actually caused by a vacuum leak.

Case #2: Jeep

Vehicle Information:
2014 Jeep Compass Sport 2.0L – MIL Lamp on.

Issue + Repair History:

• Intermittent P2173 code and idle up to 2000 RPM with the electronic throttle control light illuminating.
• Issue was worse when the engine was cold.
• Found and fixed a vacuum leak at the intake manifold gaskets, which were previously improperly reused and covered in silicone.
• Reflashed ECM and performed throttle body relearn.
• Customer reported the problem recurred once after initial fix.

Suggestions to Fix Issue:

• Check and ensure the oil level is good and clean.
• Replace the throttle body, specifically with an OEM part, and avoid certain aftermarket brands.
• Monitor the TPS signals for accuracy and cleanliness.

Final Fix:
Despite not being able to replicate the issue, the technician replaced the throttle body with an OEM part and performed a relearn based on community suggestions. The customer reported improved performance afterward.

Case #3: Dodge

Vehicle Information:
2006 Dodge Charger SXT 3.5L – Experiencing cutting out, unable to exceed 55 mph when ECT light flashes.

Issue + Repair History:

• The car would intermittently only go up to 55 mph when the ECT light started flashing.
• Smoke testing of the intake revealed no leaks initially.
• Wiring to the throttle body, MAP, and TP sensors checked with no issues found.

Suggestions to Fix Issue:

• Reconfirm if the EGR tube seal (blue) is in place and not split, located at the top rear of the intake plenum.
• Consider the possibility of an EGR issue, as it’s not uncommon for the EGR to stick and generate the P2173 code.
• Block off and redrive the EGR for confirmation if necessary.

Final Fix:
Upon rechecking for vacuum leaks and smoking the intake again, a leaking EGR tube o-ring going to the intake was discovered. After repairing this, the vehicle’s performance improved. The technician noted the importance of having a smoke machine for diagnosing vacuum, oil, and air leaks.

Case #4: Chrysler

Vehicle Information:
2013 Chrysler 200 Touring 2.4L – Experiencing hesitation, stall, and MIL Lamp on.

Issue + Repair History:

• Code P2173 was scanned, indicating high airflow/vacuum leak.
• The car lost power intermittently, with the traction light coming on during these episodes.
• When the traction light was off, the car ran fine.
• Vacuum leaks were searched for but not found. Throttle plate responses appeared good on the scanner.

Suggestions to Fix Issue:

• Double-check for vacuum leaks, especially at the intake gaskets, and consider using a smoke test.
• Ensure the EGR tube seal is correctly in place and not split.
• Drive with the scanner connected to monitor throttle position and MAP sensor voltages.
• Consider potential issues with the throttle body or PCV valve.
• Inspect the brakes and the power brake unit for issues, especially when the traction control light is on.
• Evaluate cam phaser functionality and ensure correct oil is used as it could affect vacuum and variable cam timing.
• Pressurize the exhaust and check for leaks, especially near O2 sensors.
• Disable the ABS system to see if the power loss issue related to traction control resolves.
• Check wheel speed sensors and tire size for traction control triggers.
• Update PCM and consider replacing the throttle body as a frequent fix for similar issues.

Final Fix:
The vehicle was sent to the dealer for a new PCM and programming. After this intervention, the car was reported to be performing well.

Case #5: Dodge

Vehicle Information:
2003 Dodge Ram 2500 5.7L – Experiencing poor idle quality.

Issue + Repair History:

• The truck displays no power and erratic idle 2-3 times a week.
• The issue temporarily resolves by turning the ignition off, then it idles and drives normally.
• The dealer attempted to repair it by flashing the PCM, but the problem persisted.

Suggestions to Fix Issue:

• Check for a cracked intake manifold, which could lead to vacuum leaks.
• Ensure all air intake hose clamps are seated tightly and check for any cracks or holes.
• Consider potential issues with the MAP sensor affecting barometric pressure readings and fuel calibrations.
• Inspect valve springs, as breaking could cause erratic vacuum results.
• Check the PCV valve for proper seating, missing or cracked o-rings, and ensure it’s not stuck.
• Examine the TPS for glitches or inconsistencies.

Final Fix:
The plenum was found to be cracked on the bottom side, discovered through the use of propane after unsuccessful smoke testing. The dealer was unaware of this common issue, but the fix was successful after addressing the plenum crack.