Powertrain, generic · Transmission

P0726 Engine Speed Input Circuit Range/Performance

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. P0726 means the engine speed value is present but implausible. The Allison 1000, which reads its own sensor, flags a jump of 600 rpm within 0.15 s or noise of ±650 rpm, with the engine above 600 rpm and a gear engaged, after two trips. Saab's 9-3 of 2000, which receives the value over the bus, flags more than 7200 rpm for at least 10 s. The converter clutch is then locked out and shifts may be harsh. No signal at all is P0727.

Likely causes

Engine speed sensor at the transmission (Allison) dirty or faulty, loose contact
Interference (shielding, ground)
Wrong bus value from the engine module (crankshaft sensor problem)
Transmission module

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

P0725P0727P0728P0716P0335

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