Powertrain, generic · Transmission

P0725 Engine Speed Input Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The transmission module needs engine speed for converter slip, shift quality and to check the turbine speed. Today it almost always arrives over CAN from the engine module with a validity flag; only GM's 2007 Allison 1000 tables show a separate engine speed sensor read by the transmission module. P0725 is the general fault of this input; with CAN it means the engine module marks its speed value as invalid. Saab's Aisin transmissions and a 2006 GM table set it after about 4 s, the GM table with immediate MIL. A Saab bulletin notes that behind P0725 there is always a crankshaft or camshaft sensor code in the engine module (P0016, P0335–P0339) – so read the engine module first. Limp mode follows; a completely missing CAN message is U0100.

Likely causes

Crankshaft or camshaft sensor fault in the engine module (speed invalid there)
CAN fault between engine and transmission module (wiring, termination, connector)
Engine module software or fault
Transmission module faulty

Symptoms

  • Transmission warning lamp, possibly check engine light
  • Torque converter clutch locked out
  • Harsh shifts or limp mode
  • Often an engine code (crankshaft sensor) as well

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

engine speed signalcan bustransmission control module

Related codes

P0726P0727P0728P0335U0100

References: saabwisonline.com, saabwisonline.com, gsi.ext.gm.com, law.cornell.edu.