P20CD code meaning
Exhaust Aftertreatment Fuel Injector A Control Circuit Low
Powertrain system Generic code P20xx codes Check engine light
What P20CD means
Here the control line of the hydrocarbon doser has a short to ground. GM's diesel tables 18OBDG04 and 25OBDG04A test the output while the driver is off: if the voltage drops below about 2 V, the line is touching ground. GM rates it Type A, which lights the MIL after one trip, and the fault only clears after a calibrated count of good tests or a control-module reset. The LML/LGH Duramax lists it as Type B. A grounded line can make the doser open whenever its supply side is switched on, so fuel may enter the exhaust uncontrolled; that is why it is treated more strictly than the open circuit (P20CB) or the short to power (P20CE).
P20CD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P20CD
- Check engine light on after a single trip
- Doser disabled, no active regeneration
- Possible fuel smell or smoke from the exhaust
Common causes of P20CD
- Most likelyControl wire chafed through against the frame or exhaust
- PossibleWater or salt in the doser connector bridging to ground
- Less likelyInternal short in the doser solenoid
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Aftertreatment fuel injector
What each part of P20CD means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| CD | The exact fault in that area. |
What to do next
- Note P20CD 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 P20CD
What does P20CD mean?
P20CD means "Exhaust Aftertreatment Fuel Injector A Control Circuit Low". Here the control line of the hydrocarbon doser has a short to ground. It is a generic code, so it means the same on every make.
Is it safe to drive with P20CD?
Drive gently and only to a workshop. With P20CD the car can go into limp mode (reduced power) to protect itself.
Will P20CD fail an emissions test?
Yes, it can. P20CD 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 P20CD to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P20CD clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.