Powertrain, generic · Auxiliary emission controls

P046D EGR Sensor A Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. Which part EGR sensors A and B are depends on the maker: sensor A is usually the position sensor of EGR valve A; GM's Duramax diesels of 2017/18 use sensor B for the coolant temperature sensor at the inlet of the high-pressure EGR cooler, FCA for the position sensor of the low-pressure valve. P046D means brief excursions of sensor A out of its valid range, too short for P0405/P0406. Ford petrol engines from 2020 set it when the position signal stays above 95 % or below 5 % of its range for just 0.4 s, whereas 4 s set P0405/P0406; the check runs continuously during the EGR monitor above 8.25 V and 400 rpm. EGR is then switched off.

Likely causes

Loose contact or corrosion at the EGR valve connector
Chafed wire with brief short to ground or positive
Position sensor in the valve worn
Disturbed 5 V reference

Symptoms

  • Check engine light on, may come and go
  • Usually no noticeable change
  • Occasional jerking when EGR switches off

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–600
Time0.3–2 h

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

Parts involved

egr valve position sensoregr valvesensor wiringengine control module

Related codes

P046CP0405P0406P0409P046FP044E

References: fordservicecontent.com, law.cornell.edu, newtonnet.co.uk.