P2904 on 2011-2019 Fiat Uno — Transmission Fluid Temperature Sensor "C" Circuit Low
1 vehicles · 1 makes · $350-$1,200 repair
How to diagnose and fix P2904: most-reported vehicles
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Fiat Uno · 2011–2019
The single-clutch automated manual offered on the Novo Uno (Dualogic on the 1.4 Fire Evo, GSR on the 1.3 Firefly 'Uno Drive') is the model's most expensive weak point. Chronic failure modes documented by Brazilian transmission specialists include worn or mis-calibrated clutch actuators causing slipping and jerky engagement, hydraulic pressure loss from leaks (pump shuts down, codes P0942/P2712), failed gear/clutch position sensors (P0805/P0806, P0715/P0725) and TCU faults that force the transmission into emergency mode or drop it into neutral while driving. It became serious enough that in 2019 Fiat recalled 11,669 vehicles across 8 models — including 916 Uno 1.3 GSR units, model years 2017-2018 (chassis 796635 to 835113) — because the transmission could shift to neutral involuntarily, causing sudden loss of drive.
Common Symptoms
- Transmission drops into neutral by itself while driving
- Jerky or delayed gear engagement
- Clutch slipping during shifts
- Reverse gear refuses to engage
- Gearbox warning light with transmission stuck in emergency mode
How to Fix
For 2017-2018 GSR cars: confirm the official recall (replacement of the gear selector sensor, ~1 hour, free) was performed. For chronic faults: scan the TCU for stored codes first; many problems are resolved by clutch actuator recalibration or replacement and hydraulic fluid/leak service rather than full transmission replacement. Worn clutches must be replaced with actuator recalibration. Use a shop experienced with Fiat Dualogic/GSR — incorrect calibration is a common cause of repeat failures.
Sources for this issue (1)
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P2904 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2904 mean?
P2904 stands for "Transmission Fluid Temperature Sensor "C" Circuit Low." This generic powertrain code sets when the Powertrain Control Module (PCM) or Transmission Control Module (TCM) detects that the voltage signal from the "C" transmission fluid temperature (TFT) sensor circuit is lower than the expected/calibrated range. A low circuit reading typically corresponds to an implausibly high fluid temperature indication, signaling a short to ground, a sensor fault, or a wiring problem in that temperature-sensing circuit.
What are the most common causes of P2904?
The most common causes of P2904 are: Short to ground in the TFT 'C' sensor signal wiring or connector, Failed/out-of-range transmission fluid temperature sensor, Corroded, damaged, or loose sensor connector pins, Damaged wiring harness (chafed or pinched wires) in the transmission circuit, Low or contaminated transmission fluid affecting sensor readings, Faulty PCM/TCM (less common). The specific cause varies by vehicle.
How much does it cost to fix P2904?
Repair costs for P2904 range from $350 to $1,200, depending on the vehicle and root cause.
Which vehicles are affected by P2904?
Au7o has documented P2904 across 1 vehicle models from 1 manufacturers: Fiat.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.