Exhaust Aftertreatment Fuel Injector Control Circuit Low
The P20D3 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 used in diesel engines to introduce fuel into the exhaust stream for regeneration of the diesel particulate filter (DPF) or to raise exhaust temperature for selective catalytic reduction (SCR) systems. A low circuit condition typically means the voltage is below the expected range, often due to a short to ground, open circuit, or faulty injector.
01. Most Common Causes
- Faulty exhaust aftertreatment fuel injector
- Open or shorted wiring in the injector control circuit
- Corroded or damaged connector at the injector
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Possible DPF regeneration issues or increased exhaust smoke
- Engine may enter limp mode or have reduced power
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data to confirm P20D3.
Step 2: Visually inspect the injector and its wiring harness for damage, corrosion, or loose connections.
Step 3: Using a multimeter, check the injector control circuit for voltage and resistance; compare to manufacturer specs.
Step 4: Test the injector itself by measuring its resistance; replace if out of spec.
Step 5: If wiring and injector are okay, check PCM for faults or perform a continuity test from PCM to injector.
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, increased emissions, and potential engine performance issues. You may be able to drive short distances, but have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, depending on whether the injector needs replacement or if it's a wiring repair. Labor and parts vary by vehicle make and model.