Powertrain, generic · Transmission

P093A Hydraulic Accumulator Solenoid Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

The control circuit of the solenoid that opens or locks a hydraulic accumulator in the gearbox is open. Such accumulators store pressurised fluid, for example to keep clutches applied during engine stop-start, as GM's patents on a stop-start accumulator and an accumulator with solenoid valve describe. No manufacturer documents P093A publicly. GM uses its own P171A for the same fault on the surge accumulator solenoid: failed if circuit impedance exceeds 200 kOhm in 32 of 40 samples, Type B with MIL after two trips. P093B and P093C are the low and high faults, P093D the performance fault. Stop-start is usually disabled, and the first restart may engage with a jolt.

Likely causes

Accumulator solenoid coil open
Connector unplugged or wire broken between module and solenoid
Fault in the internal transmission harness or lead frame
Output driver in the control module failed

Symptoms

  • Warning light on (after repeated detection)
  • Engine stop-start no longer active
  • Jolt or slip when driving off after an engine 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

P093BP093CP093DP0944

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