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Serious Gearbox Fault:
P171E and P171F indicate the Multitronic transmission is receiving no signal or an implausible signal from Input Shaft Speed Sensor 2. This directly affects ratio control and can result in limp mode or loss of drive.
What Do Fault Codes P171E & P171F Mean?
On Audi Multitronic (CVT) gearboxes, fault codes P171E and P171F relate to Transmission Input Shaft Speed Sensor 2. The gearbox control unit compares multiple speed signals; when this sensor drops out or reports unrealistic data, the system cannot safely control the transmission.
Common Causes
- Failed input shaft speed sensor 2
- Internal wiring damage inside the gearbox
- Signal short to ground or interference
- Transmission Control Unit (TCU) processing fault
- Contaminated or degraded CVT fluid affecting sensor readings
Symptoms You’ll Notice
- PRNDS flashing on the instrument cluster
- Gearbox limp mode or restricted driving
- Juddering or hesitation on pull-away
- Loss of drive when hot
- P171E / P171F logged during diagnostics
Our Audi Multitronic Repair Process
These faults are regularly misdiagnosed as complete gearbox failure. We perform live data comparison, signal plausibility testing, wiring continuity checks, and TCU diagnostics before condemning any major components. Many P171E / P171F cases can be resolved without replacing the gearbox.