Fix P2106: Mechanic’s solutions that WORKED

The P2106: Throttle Actuator Control System – Forced Limited Power indicates a problem with the Throttle Actuator Control System, which can lead to reduced engine power. It is often caused by issues with the throttle actuator control module, throttle body, or related electrical components. Addressing this code is important to maintain proper engine performance.

P2106 quick overview

Meaning	P2106: Throttle Actuator Control System – Forced Limited Power
Is it serious?	This code can be moderately serious as it may cause reduced engine power and affect drivability. It should be addressed to prevent potential performance issues.
Possible causes	– Faulty throttle actuator control module – Throttle body issues such as carbon buildup or malfunction – Wiring or electrical connection problems in the throttle control circuit – Vacuum leaks in the intake system – Electronic throttle control sensor problems
How to diagnose?	Scan for Codes: Use a diagnostic scanner to retrieve and document the P2106 fault code. Visual Inspection: Inspect the throttle body and its wiring and connections for visible issues. Check Throttle Body: Examine the throttle body for carbon buildup or mechanical problems. Test Electrical Connections: Check the electrical connections related to the throttle control system. Vacuum Leak Test: Perform a vacuum leak test on the intake system. Throttle Actuator Testing: Test the throttle actuator control module for proper operation. Clear Codes: After repairs or inspections, clear the fault code and monitor for its return.

How to fix P2106 – learn from mechanics

I looked into P2106 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: Ford

Vehicle Information: 2004 Ford F-150 FX4 5.4L

Issue + Repair History: The vehicle had a code C1230, and it triggered a P2106 when reaching 40MPH. The speedometer was reading correctly, and the VSS reading in the ECM was consistent. The P2106 code was thought to be related to a VSS issue, but there were no typical speed sensor problems in the rear differential.

Other OBD2 Codes + Test Results: C1230

Suggestions to Fix Issue:

• Check for aftermarket modifications on the truck that might be causing installation problems.
• Investigate the rear speed sensor, even if the speedometer is working correctly.
• Understand that the speedometer can receive data from the transmission or transfer case, not just the VSS in the rear differential.
• Use resources like iATN for additional information on Ford vehicles.

Final Fix: After inspecting the intake and fuel system and finding no cause for the P2106, it was determined that the C1230 code could cause the P2106 and throttle restrictions. The ABS code C1230 was addressed by replacing the sensor in the differential and repairing the broken wire to it. This repair resolved the ABS issue and prevented the P2106 from setting, resulting in improved vehicle performance.

Case #2: Lincoln

Vehicle Information: 2006 Lincoln Town Car Executive L 4.6L

Issue + Repair History: The car, from a limo company, had a complaint of rough idle and a wrench light on. It came in with code P2106. After a road test, no problems were found, and the owner went to a dealer who replaced the throttle body and mentioned a faulty EGR valve. The car returned to the original shop, and they replaced the EGR valve. The next day, the wrench light was back on, and there were issues with rough idle, deceleration, and idle. It felt like a misfire, but no misfire codes were present, even in mode six. It also felt like the transmission was locking up.

Related Repair History: Throttle body replaced. EGR valve replaced.

Suggestions to Fix Issue:

• Check for additional trouble codes.
• Investigate if the car has an accelerator position sensor.
• Consider checking for PCM updates and performing an idle relearn after the throttle body replacement.
• Examine the air flow sensor readings on a scanner, as it may be an air flow problem rather than an ignition issue.

Final Fix: The customer returned to the dealer, and they replaced the EGR valve again. The car was fine after this second EGR valve replacement, and the issue was resolved. It’s suspected that the dealer may have done more than just replace the EGR valve, as the customer received their EGR valve back, and it appeared to be a Ford part reboxed by Standard. Despite the uncertainty about the valve itself, the customer was satisfied with the repair.

Case #3: Ford

Vehicle Information: 2004 Ford F-150 FX4 5.4L

Issue + Repair History: The vehicle initially had a P0722 code, and the output speed sensor was replaced. Later, it returned with the same P0722 code and an additional P2106 code. The customer reported that three times in the last month, the wrench light and the engine light would come on, and the vehicle would lose power. Turning the truck off and restarting it would temporarily resolve the issue.

Related Repair History: Output speed sensor replaced.

Suggestions to Fix Issue:

• Clean the throttle body.
• Check for an intermittent signal from the output speed sensor by inspecting the wiring from the sensor to the TCM.
• Consider replacing the coils, as the 5.4L engine in the F-150 can have similar coil problems.
• Replace all coils and use Motorcraft plugs if necessary.
• If cleaning the throttle body doesn’t permanently resolve the issue, consider replacing the throttle body.

Final Fix: After cleaning the throttle body and returning the vehicle to the customer, the issue persisted. Ultimately, the throttle body was replaced, and the problem was resolved.

Case #4: Dodge

Vehicle Information: 2003 Dodge Ram 2500 5.7L

Issue + Repair History: The Dodge pickup was experiencing issues with acceleration and idling. The throttle plate was not moving, and there was no vacuum in the intake. The throttle assembly was replaced, and a relearn was performed, but the problem persisted. With the key on engine off (KOEO), the TPS sensors were in spec but would not change because the throttle plates wouldn’t move.

Other OBD2 Codes + Test Results: P2106 – ETC forced limited power P2172 P2108 – ETC module performance P0222 – TPS 2 low P0123 – TPS 1 high

Suggestions to Fix Issue:

• Investigate the TPS (Throttle Position Sensor) codes P0222 and P0123 by checking the TPS voltages and ensuring they are correct.
• Address the P2108 code, which indicates a potential internal PCM (Powertrain Control Module) fault. Consider replacing the PCM if this code persists.
• Examine the intake for possible splits or damage, as a broken intake can affect throttle operation. Smoke testing the intake is recommended.
• Check for reversed TPS voltage signals, as it might be possible that the TPS voltages are backward.
• Consider checking for broken valve springs in the engine, which can trigger a fail-safe mode and affect throttle operation.
• Use a factory scan tool to command the ETC (Electronic Throttle Control) to function and test the throttle plate movement.

Final Fix: The issue was resolved by discovering that the intake was split underneath, which was affecting the vacuum and throttle plate operation. After addressing the split intake, the problem was resolved, and the vehicle operated normally.

Case #5: Hyundai

Vehicle Information: 2007 Hyundai Santa Fe GLS 2.7L

Issue + Repair History: The vehicle had a severe acceleration issue and would not accelerate properly. The following issues were observed:

• 5V reference to TPS A was low coming out of the PCM (Powertrain Control Module).
• A trouble code P0122 was present, indicating TPS Circuit A low input.
• Accelerator pedal position sensor A was also not receiving a 5V reference and was getting only 130mV.
• Cutting the 5V reference line at the PCM did not resolve the issue, indicating that the wiring and TPS were not the problem.
• Adding 5V directly to the circuits did not fully resolve the problem, as the PCM detected incorrect 5V references and dragged the voltage down.
• Replacing the PCM and throttle body did not solve the issue.
• The vehicle had been in an accident, which affected the right front (RF) but not the wiring near the affected area.

Other OBD2 Codes + Test Results: P0641 P0346 P2106

Suggestions to Fix Issue:

• Check the voltage of pedal positioning sensor A and B to ensure they are close to opposite values.
• Examine the ground wires on the affected side (RF) and make sure no wires were pinched in that area.
• Investigate the possibility of harness damage or pinched wires in the area where the harness comes through, especially for the pedal and related components.
• Perform a fuel sample to check for fuel contamination with water or diesel fuel.
• Drop test all grounds to identify any potential issues.
• Check for wiring and ground issues, especially if the bodywork involved attaching a ground to a painted surface.

Final Fix: The issue was resolved by replacing the engine wiring harness. The PCM was unable to produce a 5V reference to the throttle sensor until the harness was replaced. Despite extensive wire checking in the damaged area and elsewhere, no specific reason for the voltage drop was found. Replacing the harness resolved the problem, and the vehicle operated correctly.

Advice	Diagnostic Step Description
Check pedal positioning sensor voltages	Verify that pedal sensors A and B have voltages close to opposite values.
Inspect wiring and grounds	Examine the wiring for damage, especially in areas affected by accidents, and ensure proper grounds.
Perform a fuel sample	Check for fuel contamination with water or diesel fuel.
Drop test all grounds	Test all ground connections for potential issues.
Consider TSBs and updates	Check for manufacturer Technical Service Bulletins (TSBs) and updates related to the fault code.
Replace engine wiring harness if necessary	If no other issues are found, consider replacing the engine wiring harness, especially if the PCM cannot produce a 5V reference.