Powertrain, generic · Transmission

P093B Hydraulic Accumulator Solenoid Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

The control circuit of the hydraulic accumulator solenoid reads low, usually a control wire shorted to ground or a coil with very low resistance. No manufacturer documents P093B publicly. GM covers the same fault on its surge accumulator solenoid with P171B: failed short to ground when circuit impedance drops below 0.5 Ohm in 32 of 40 samples, Type B with MIL after two trips. The accumulator holds pressurised fluid so clutches stay applied during an engine auto-stop, as GM's stop-start accumulator patent explains. P093A is the open-circuit fault, P093C the high fault and P093D the performance fault. A grounded control line can leave the valve permanently energised, and stop-start is typically switched off.

Likely causes

Solenoid control wire shorted to ground
Solenoid coil shorted internally
Output driver in the control module failed

Symptoms

  • Warning light on (after repeated detection)
  • Engine stop-start no longer active
  • Harsh engagement after restart

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,200
Time1–5 h

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

Parts involved

hydraulic accumulator solenoidwiring harnesstcm

Related codes

P093AP093CP093D

References: law.cornell.edu, gsi.ext.gm.com, patents.google.com.