Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P05FA Stop-Start Status Signal Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

A discrete stop-start status line tells the engine module (or another module) whether stop-start is active, inhibited or has just stopped the engine. On most current cars this status travels over CAN instead, so a hard-wired line and these codes are rare; no manufacturer document available to us uses P05F9–P05FB. CARB names stop-start as its example of an 'emissions neutral' reaction: a module that simply disables stop-start when a fault appears may report it without the check engine light, which is what Ford does for its stop-start codes. P05FA means the status line stays below its lower limit – a short to ground or a missing pull-up supply. Stop-start is then disabled.

Likely causes

Status line shorted to ground
Sending module pulls the line to ground permanently (faulty output)
Moisture or corrosion in the connector

Symptoms

  • Stop-start does not work
  • Stop-start indicator or message in the cluster

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–300
Time0.5–2 h

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

Parts involved

stop start status linebody control moduleengine control module

Related codes

P05F9P05FBP05FF

References: law.cornell.edu, fordservicecontent.com.