Powertrain, generic · Transmission

P0748 Pressure Control Solenoid A Electrical

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Pressure control solenoid A sets line or clutch pressure by current; most are 'normally high', so with no current – as in limp mode – maximum pressure applies. 'A' is usually the line pressure valve, on GM clutch-to-clutch transmissions (6T, 8L, 9T) the pressure valve of clutch 1. Ford does not use P0745–P0749 but P0960–P0963. P0748 is the electrical code of this valve, checked by current, duty cycle or terminal voltage: Subaru after 0.14 s with MIL after two trips and limp mode in third, Allison against an 8 Ω current model after 125 ms, GM's diesel 4L80-E for a duty cycle outside 0.5–95 % for 2 s without MIL. The valve is switched off – maximum pressure, harsh shifts, frozen adaption, often a fixed gear (Saab AF40: second and reverse) and reduced torque. Saab's 2010 9-5 uses P0748 for a current deviation instead.

Likely causes

Harness or transmission connector (corrosion, oil, chafing)
Pressure control solenoid faulty (resistance out of spec)
Internal harness, electronic module or mechatronic unit
System voltage too low
Transmission module driver

Symptoms

  • Harsh shifts or engagement (maximum pressure)
  • Limp mode in a fixed gear
  • Transmission warning or check engine light
  • Reduced engine power (torque limit)

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–1,500
Time1–5 h

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

Parts involved

pressure control solenoid atransmission valve bodytransmission wiringtransmission control module

Related codes

P0745P0746P0747P0749P0962P0963

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