What Does P20CD Mean?
The PCM has detected abnormally low voltage in the exhaust aftertreatment fuel injector control circuit. This indicates a short to ground or excessive current draw in the circuit.
Common Causes
35%
Shorted injector wiring harness to ground (chafed against metal)
30%
Failed exhaust fuel injector with internal short to ground
20%
Water intrusion or corrosion in injector connector causing short
10%
Damaged PCM injector driver circuit
5%
Pinched or damaged harness during previous repair work
Diagnostic Steps
1
Step 1: Disconnect exhaust fuel injector connector and measure resistance from injector control pin to ground (should be infinite/open)
2
Step 2: Measure resistance of injector coil with connector disconnected (typically 2-10 ohms); low resistance indicates shorted coil
3
Step 3: Inspect wiring harness for damage, especially where it contacts exhaust components or frame rails
4
Step 4: Check injector connector and pins for moisture, corrosion, or contamination indicating water intrusion
5
Step 5: With injector disconnected, check for short to ground on vehicle harness side from control wire to chassis ground
Estimated Repair Cost
$150 - $1,600
Parts + labor, varies by vehicle and location
The PCM has detected abnormally low voltage in the exhaust aftertreatment fuel injector control circuit. This indicates a short to ground or excessive current draw in the circuit.
The most common cause of P20CD (Exhaust Aftertreatment Fuel Injector "A" Control Circuit Low) is: Shorted injector wiring harness to ground (chafed against metal)
Typical repair costs for P20CD range from $150 to $1,600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to operate but DPF regeneration capability is compromised. Continued operation may lead to DPF clogging and reduced engine performance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P20CD to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control - Diesel Particulate Filter Regeneration
Difficulty
Type
Generic (SAE)
Recommended Tools
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