Powertrain, generic · Transmission

P0727 Engine Speed Input Circuit No Signal

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
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. P0727 means the engine speed signal is missing although the transmission is turning. The Allison 1000 flags under 61 rpm for 4 s with turbine speed of 400 rpm or more, after two trips; Saab's 9-3 of 2000 input speed above 2000 rpm for more than 5 s without engine speed; a 2006 GM table the CAN engine speed failing to answer. The module then works without converter slip information, usually locks out the converter clutch and may enter limp mode.

Likely causes

Engine speed wire or connector open, or own sensor (Allison) faulty
CAN communication between engine and transmission module disturbed
Crankshaft sensor fault in the engine module
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€60–400
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

P0725P0726P0728P0717U0100

References: gsi.ext.gm.com, gsi.ext.gm.com, saabwisonline.com.