Carbon buildup or contamination on the throttle body internal potentiometer tracks; Wear or degradation of the potentiometer resistive tracks inside the electronic throttle body; Corroded, chafed, or loose wiring in the throttle body harness connector or associated circuits; Poor electrical connection at the throttle body connector pins; Failed electronic throttle body assembly (internal sensor or motor fault); Engine control module (ECM) software issue or internal fault (rare)

DTC codes / Volkswagen codes / P1171

P1171 · VolkswagenThrottle Actuation Potentiometer Signal 2 Range Performance

Q: What does code P1171 mean?

Throttle Actuation Potentiometer Signal 2 Range Performance. P1171 on Volkswagen vehicles indicates that the engine control module (ECM) has detected an implausible or out-of-range signal from the second throttle actuation potentiometer inside the electronic throttle body. The ECM compares this signal with the first potentiometer and expects them to correlate; when the second signal deviates beyond a calibrated threshold, the code is stored and the engine may enter a reduced-power mode.

P1171 on Volkswagen vehicles indicates that the engine control module (ECM) has detected an implausible or out-of-range signal from the second throttle actuation potentiometer inside the electronic throttle body. The ECM compares this signal with the first potentiometer and expects them to correlate; when the second signal deviates beyond a calibrated threshold, the code is stored and the engine may enter a reduced-power mode.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the electronic power control (EPC) warning light or check engine light
Reduced engine power or limp mode, often limiting RPM to around 1500–2000
Hesitation or stumble when pressing the accelerator pedal
Unstable or surging idle speed
Poor throttle response or delayed acceleration
Often no symptoms besides the warning light, especially if the fault is intermittent

Common causes, most likely first

Carbon buildup or contamination on the throttle body internal potentiometer tracks
Wear or degradation of the potentiometer resistive tracks inside the electronic throttle body
Corroded, chafed, or loose wiring in the throttle body harness connector or associated circuits
Poor electrical connection at the throttle body connector pins
Failed electronic throttle body assembly (internal sensor or motor fault)
Engine control module (ECM) software issue or internal fault (rare)

How to diagnose and fix it

Perform a visual inspection of the throttle body connector and wiring for corrosion, damage, or loose pins; clean and secure as needed
Use a scan tool to read live data for both throttle position sensors (TPS1 and TPS2) and compare their voltages throughout the pedal travel; look for dead spots or non-linear response
Remove the throttle body and clean the internal potentiometer tracks and throttle plate with appropriate electronic cleaner and a soft brush; reinstall and perform a throttle body adaptation
Check the resistance and continuity of the throttle body harness circuits between the ECM and throttle body according to the factory wiring diagram
If cleaning and wiring repairs do not resolve the issue, replace the electronic throttle body assembly with a quality OEM or equivalent part
After replacement, perform a throttle body adaptation using a diagnostic scan tool to relearn the closed and open positions
If the fault persists after all other steps, diagnose the ECM and its software; update or replace only if confirmed faulty

Throttle body cleaning often fixes P1171

Many technicians replace the throttle body immediately, but carbon contamination on the potentiometer tracks is a frequent and correctable cause that can be resolved with careful cleaning.
The code can be set by intermittent wiring faults that only appear under vibration or temperature changes, so a wiggle test of the harness while monitoring live data is essential.
A dirty throttle body may cause both P1171 and P1172 (throttle actuation potentiometer signal 1) or other throttle-related codes; addressing the root cause prevents recurrence.
After any service that affects the throttle body, a throttle body adaptation must be performed; skipping this step can lead to poor running and repeat codes.
On some Volkswagen models, a weak battery or charging system issue can cause voltage spikes that disrupt throttle body signals, so check battery health and grounds before condemning the throttle body.

Can I keep driving with P1171?

If the vehicle is in limp mode with severely reduced power, avoid highway driving and seek repair promptly. If the only symptom is the warning light and the car drives normally, you may drive cautiously to a workshop, but avoid aggressive acceleration or heavy loads until diagnosed.

Tools that help

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Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.