P046C code meaning
EGR Sensor A Circuit Range/Performance
Powertrain system Generic code P04xx codes Check engine light
What P046C means
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. P046C means the signal of sensor A is electrically valid but implausible. GM's diesels (6.6-litre Duramax LML and others from 2014) set it when the actual valve position deviates from the target by 5 % or more for 8 s, with offset learning completed and at least 11 V (MIL after two trips). Ford uses P0405/P0406/P046D for sensor A instead. EGR is then switched off or limited.
P046C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P046C
- Check engine light on
- EGR switched off, possibly higher NOx
- Rarely jerking or lack of power
Common causes of P046C
- Most likelyEGR valve coked and stiff, actual position does not follow
- PossiblePosition sensor worn or offset shifted
- PossibleContact resistance at connector or 5 V supply
- Less likelyValues not relearned after valve replacement
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR valve position sensorEGR valveSensor wiringEngine control module
What each part of P046C means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 6C | The exact fault in that area. |
What to do next
- Note P046C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P046C
What does P046C mean?
P046C means "EGR Sensor A Circuit Range/Performance". Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. It is a generic code, so it means the same on every make.
Is it safe to drive with P046C?
Drive gently and only to a workshop. With P046C the car can go into limp mode (reduced power) to protect itself.
Will P046C fail an emissions test?
Yes, it can. P046C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P046C to fix?
Difficulty: medium. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P046C clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.