Powertrain, generic (extended)

P2D97 Starter/Generator Phase Z Current Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2D97 is the last of the three low codes: the Z-phase current sensor of the starter/generator reports a value under the bottom of its valid window. Because the machine both drives the engine and charges, its phase current is signed, so a low fault stands for an impossible negative reading or a collapsed output, not for a weak current. Z is no mere placeholder: Mazda's bulletin 01-004-25 for its integrated starter generator lists the stator driver circuits in a U-V-W group and a separate X-Y-Z group. No manufacturer documents P2D97 publicly. In GM's eAssist analogue the low codes trip below -440 A after roughly 42 ms, Type B. Suspect a grounded signal lead or a lost sensor supply. High side: P2D94; X and Y low: P2D95, P2D96.

Likely causes

Phase Z sensor signal lead shorted to ground or to the machine housing
Sensor supply interrupted by an open wire or a pushed-back terminal
Phase Z current sensor output stuck at the bottom of its range

Symptoms

  • Warning lamp or MIL, typically after the fault has repeated on a second trip
  • Electric boost and recuperation reduced or switched off
  • No automatic engine stop, or restarts via the conventional starter

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–2,000
Time0.5–4 h

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

Parts involved

starter generator phase z current sensorwiring harnessstarter generator control module

Related codes

P2D94P2D95P2D96P2DC5P2DC6P2D9A

References: static.nhtsa.gov, gsi.ext.gm.com.