Powertrain, generic · Auxiliary emission controls

P04E2 Crankcase Ventilation Hose Connection Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The crankcase ventilation (PCV) system routes blow-by gas from the crankcase into the intake; CARB requires a disconnection between crankcase and intake to be detected. GM's 2.0-litre LSY has a pressure sensor in the PCV hose: with the hose connected it must see a pressure drop that grows with air flow, plus pressure pulses from the pistons. Ford reports the same sensor type as crankcase pressure sensor A (P051A ff). P04E2 means the sensor signal is too low: GM's LSY sets it at 4.3 % of 5 V or less (about 0.22 V) in 1280 of 1600 samples, MIL after two trips. With this ratiometric sensor an open signal line also reads low, as does a missing 5 V reference. The disconnection check P04DB is then suspended.

Likely causes

Signal line open or shorted to ground
5 V reference open or shorted (often shared with other sensors)
Connector not latched or corroded
Sensor faulty

Symptoms

  • Check engine light on
  • Disconnection check P04DB does not run
  • Usually no change in driving

Repair estimate

DifficultyEasyDIY possible
Parts and labour€50–250
Time0.3–1.5 h

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

Parts involved

crankcase ventilation hose sensorsensor wiringengine control module

Related codes

P04E3P04E1P04E4P04FBP04DBP051C

References: gsi.ext.gm.com, fordservicecontent.com, law.cornell.edu.