Powertrain, generic · Hybrid propulsion

P0A73 Generator Phase V Current Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A73 indicates that phase V of the hybrid generator delivers or reports too little current under load. No manufacturer documents P0A73 publicly. On inverters that measure only phases V and W, a low V reading has a knock-on effect: the calculated U current is wrong as well, so the generator torque control loses accuracy. A Caterpillar patent shows the logic for three-sensor systems, where a near-zero reading plus a violated zero-sum identifies the failed sensor; a Toyota patent compares a control sensor with a monitoring sensor and the current command. CARB requires circuit monitoring of electric drive components. P0A74 is the high side, P0A70 and P0A76 phases U and W, P0A72 the general code. Charging and engine start can suffer.

Likely causes

Generator phase V current sensor reading near zero
Generator phase V lead or terminal open
Phase V switch in the generator inverter not conducting

Symptoms

  • Hybrid warning and MIL
  • Engine runs more often, battery charge does not recover

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–6,000
Time1.5–8 h

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

Parts involved

generator phase vinverter

Related codes

P0A72P0A74P0A70P0A76P0A6A

References: patents.google.com, patents.google.com, law.cornell.edu.