P20CD - Exhaust Aftertreatment Fuel Injector Control Circuit Low
The P20CD code indicates that the powertrain control module (PCM) has detected a low voltage condition in the control circuit of the exhaust aftertreatment fuel injector. This injector is responsible for injecting fuel into the exhaust stream to regenerate the diesel particulate filter (DPF) or to heat the selective catalytic reduction (SCR) system. A low circuit voltage typically points to a wiring issue, a faulty injector, or a problem with the PCM. This can lead to incomplete regeneration, increased emissions, and potential damage to the aftertreatment system.
01. Most Common Causes
- Faulty exhaust aftertreatment fuel injector
- Open or shorted wiring in the injector control circuit
- Poor electrical connection at the injector or PCM
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Increased exhaust emissions
- Possible DPF regeneration issues or frequent regeneration cycles
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related codes (e.g., P20CE, P20CC).
Step 2: Visually inspect the wiring and connector of the exhaust aftertreatment fuel injector for damage, corrosion, or loose connections.
Step 3: Measure the voltage and resistance at the injector connector with a multimeter. Compare to manufacturer specifications.
Step 4: If wiring is intact, test the injector by applying power and ground directly (if safe) or use a bidirectional scan tool to command the injector on.
Step 5: If injector tests bad, replace it. If wiring is faulty, repair or replace the harness. Clear codes and test drive.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can lead to incomplete DPF regeneration, causing the filter to clog and potentially resulting in costly repairs. Short trips may be okay, but the issue should be addressed promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, depending on the root cause. Replacing the injector itself can cost $100-$250 for parts, plus labor. Wiring repairs are usually less expensive.