P2165 Throttle/Pedal Position Sensor "C" Maximum Stop Performance

The P2165 trouble code indicates that the engine control module (ECM/PCM) has detected a problem with the maximum-stop performance of Throttle/Pedal Position Sensor "C".

This is an electronic throttle or accelerator-pedal monitoring fault. The important part of the description is “Maximum Stop Performance.” The ECM is checking whether Sensor C reaches and reports the expected position at the maximum-stop point of the throttle or pedal system.

P2165 does not automatically mean that the accelerator pedal or throttle body must be replaced. The code identifies an abnormality in the expected position or behavior of a sensor circuit; the actual cause can be the sensor itself, wiring, connector, mechanical travel, calibration, or the electronic throttle system.

What Does “Maximum Stop” Mean?

The term can sound more complicated than it really is.

A throttle or accelerator position sensor produces a signal representing the position of the pedal or throttle mechanism. The ECM knows approximately what signal should be present at different positions.

At the end of the permitted travel, there is a defined maximum-stop position.

The ECM can therefore check whether Sensor C reaches an appropriate value when the pedal or throttle reaches this limit.

If the sensor indicates a position that is outside the expected range, does not change correctly, or fails to reach the expected maximum-stop value, P2165 may be stored.

The exact implementation varies considerably between manufacturers.

Why Does the Vehicle Need More Than One Position Signal?

Modern electronic throttle systems commonly use multiple position signals for safety and plausibility checking.

Depending on the vehicle, the accelerator pedal may contain several position-sensor elements. The throttle body can also contain multiple throttle-position signals.

The ECM compares these signals against each other.

This redundancy is important because the accelerator pedal and throttle are no longer connected by a simple mechanical cable in many modern vehicles.

A typical electronic throttle system works approximately like this:

Accelerator pedal → Pedal position sensors → ECM → Throttle actuator → Throttle position sensors → ECM feedback

If one signal behaves differently from the others, the ECM can recognize the inconsistency and enter a reduced-power strategy.

What Does Sensor "C" Refer To?

Sensor "C" is a manufacturer-defined sensor designation.

It does not universally mean the third physical sensor or a particular connector pin.

Depending on the vehicle, the code may relate to one of the redundant accelerator-pedal position signals or another throttle/pedal position sensing circuit.

For this reason, the exact wiring diagram and manufacturer's service information are important when diagnosing P2165.

This is particularly important because replacing the wrong sensor or throttle component based only on the generic code description can waste time and money.

Common Causes of P2165

Accelerator pedal position sensor problem

If the pedal assembly contains the affected Sensor C circuit, an internal sensor fault can cause the signal to stop at an incorrect value or fail to reach the expected maximum position.

Throttle position sensor problem

On systems where Sensor C is associated with throttle position, a faulty throttle-position sensing element can produce the same type of fault.

Damaged wiring

A partially broken wire, damaged insulation, intermittent connection or excessive resistance can distort the sensor signal.

Connector problems

Loose terminals, corrosion, contamination or poor terminal tension can cause an intermittent or incorrect position signal.

Mechanical restriction

The pedal or throttle mechanism may not physically reach its intended maximum position.

Possible causes include:

• Obstruction around the accelerator pedal

• Damaged pedal assembly

• Binding throttle plate

• Carbon deposits

• Damaged throttle mechanism

• Incorrect installation

• Foreign material interfering with movement

Incorrect sensor calibration or learned values

Some vehicles require throttle or pedal position learning after component replacement, battery-related events, throttle-body service or other repairs.

If the system has lost or contains incorrect learned values, a maximum-stop plausibility check may fail.

Low system voltage

A weak battery, charging problem or unstable electrical supply can sometimes produce unusual electronic throttle and sensor faults, particularly when multiple unrelated electronic codes appear simultaneously.

ECM/PCM problem

An ECM input or processing fault is possible, but it should normally be considered after the sensor, mechanical operation, wiring and power supply have been properly tested.

Symptoms You May Experience

P2165 can produce very different symptoms depending on the vehicle and the degree of sensor disagreement.

Possible symptoms include:

• Check Engine Light

• Reduced engine power

• Poor throttle response

• Accelerator pedal response that feels abnormal

• Hesitation

• Limited RPM

• Limp mode

• Engine speed that does not respond normally to pedal movement

• Intermittent acceleration

• Difficulty maintaining engine speed

• Stalling in some situations

• Cruise control becoming unavailable

Some vehicles may detect the problem immediately and restrict throttle operation. Others may continue operating normally until the affected sensor reaches the condition that causes the maximum-stop check to fail.

Why the Maximum Position Is Important

The ECM is not simply looking for a signal that increases when you press the pedal.

It also needs to know whether the signal reaches credible limits.

Imagine that the pedal is pressed fully, but Sensor C reports a value corresponding to only 70% pedal position.

The other pedal sensor may indicate that the pedal is actually at maximum.

The ECM sees a disagreement.

Alternatively, Sensor C could reach a voltage outside the calibrated range when the pedal reaches its stop.

In either situation, the ECM may determine that the maximum-stop performance is incorrect.

This is why P2165 is fundamentally a position plausibility and performance problem.

How to Diagnose P2165

The best diagnosis begins with live data rather than immediately replacing the accelerator pedal or throttle body.

Scan all available codes

Check for additional throttle, accelerator-pedal, position-sensor, communication, voltage and engine-control codes.

P2165 may occur alongside another code that identifies the underlying electrical or mechanical problem more directly.

Check freeze-frame information

If available, examine:

• Engine RPM

• Vehicle speed

• Accelerator position

• Throttle position

• Engine load

• Battery voltage

• Sensor values

The conditions under which P2165 was stored can help determine whether the problem occurs only at maximum pedal travel or throughout the sensor's operating range.

Inspect the accelerator pedal and throttle mechanism

Make sure the pedal moves freely through its complete travel.

Check for anything physically preventing the pedal from reaching its normal stop.

On the throttle side, inspect for binding, excessive deposits or mechanical damage where applicable.

Inspect the wiring and connectors

Pay attention to:

• Broken wires

• Chafed harnesses

• Loose terminals

• Corrosion

• Water contamination

• Oil contamination

• Poor previous repairs

• Connector locking problems

Because these circuits carry low-level sensor signals, even a poor connection can create implausible readings.

Monitor Sensor C with a scan tool

Observe the sensor value while the accelerator pedal is slowly moved from released to maximum position.

The signal should generally change smoothly and predictably according to the manufacturer's specifications.

Look for:

• Sudden jumps

• Dropouts

• Dead spots

• Frozen readings

• Erratic movement

• Incorrect maximum value

• Disagreement with redundant sensor signals

A slow, controlled pedal movement can reveal problems that are impossible to see from a simple resistance test.

Compare redundant sensor signals

This is particularly important on electronic accelerator systems.

If Sensor A, B and C signals are available, compare their behavior throughout the pedal's travel.

The exact relationship between these signals is manufacturer-specific, so do not assume that all sensors should produce identical voltages.

They may intentionally use different voltage ranges or opposing signal strategies.

Do Not Assume a Bad Sensor From the Code Alone

One of the easiest mistakes with P2165 is to see “Throttle/Pedal Position Sensor C” and immediately replace the accelerator pedal.

That may fix the problem if the sensor is genuinely defective, but it is not a reliable diagnostic method.

For example, a damaged wire near the pedal could cause the exact same symptom.

A loose terminal could work normally most of the time and fail only when the pedal is moved.

A mechanical obstruction could prevent the pedal from reaching the expected maximum position even though all of the electronics are functioning correctly.

Could a Dirty Throttle Body Cause P2165?

It is possible in systems where the affected position signal belongs to the throttle body and deposits interfere with throttle movement.

However, carbon deposits do not automatically explain a P2165.

The code specifically concerns maximum-stop performance of a position-sensing system. If the throttle plate moves freely and the sensor signals are correct, cleaning the throttle body will not solve an electrical sensor problem.

Likewise, if the accelerator pedal sensor is the affected circuit, cleaning the throttle body would not address the root cause.

Does P2165 Mean the Accelerator Pedal Is Bad?

Not necessarily.

The repair could involve:

• Accelerator pedal assembly

• Throttle body

• Position sensor

• Wiring

• Connector

• Terminal repair

• Mechanical obstruction

• Throttle/pedal calibration

• Battery or charging-system issue

• ECM/PCM

The exact component depends on which sensor the manufacturer associates with Sensor C.

Calibration and Relearn Procedures

Some electronic throttle systems use learned minimum and maximum positions.

After certain repairs, the ECM may need a specific throttle or accelerator-pedal relearn procedure.

The required procedure varies widely.

Simply disconnecting the battery is not a universal substitute for a manufacturer-specified relearn.

If the throttle body or pedal assembly has been replaced, the service procedure should be checked to determine whether initialization, adaptation or calibration is required.

Can You Drive With P2165?

Driving with P2165 can be unpredictable because the fault involves an accelerator or throttle position signal.

If the vehicle has normal throttle response and only the Check Engine Light is illuminated, it may be possible to drive carefully to a repair facility.

However, driving should be avoided if there is:

• Severe loss of throttle response

• Unexpected acceleration behavior

• Major hesitation

• Stalling

• Severe reduced-power mode

• Inability to control engine speed normally

Electronic throttle systems are safety-critical. If the accelerator response becomes abnormal, the vehicle should be inspected rather than repeatedly driven in an attempt to see whether the problem disappears.

The Main Point About P2165

P2165 is not simply a “bad accelerator pedal” code.

It tells you that the ECM has detected an abnormal condition involving the maximum-stop performance of Throttle/Pedal Position Sensor C.

The correct diagnostic path is to determine exactly what Sensor C represents on that vehicle, then evaluate:

Mechanical travel → sensor signal → redundant sensor agreement → wiring/connectors → calibration/learned values → ECM input

That approach is much more reliable than replacing the pedal or throttle body based solely on the P2165 code.