Exhaust Aftertreatment Fuel Injector Control Circuit/Open
The P20D1 code indicates a problem in the control circuit of the exhaust aftertreatment fuel injector, which is used in diesel engines to inject fuel into the exhaust stream for regeneration of the diesel particulate filter (DPF) or selective catalytic reduction (SCR) system. The powertrain control module (PCM) has detected an open or short circuit in the injector's control circuit, preventing proper operation. This can lead to incomplete regeneration, increased emissions, and potential damage to the aftertreatment system.
1. 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)
2. Symptoms You Will Notice
- Illuminated check engine light
- Reduced fuel economy
- Increased exhaust emissions
- Possible DPF regeneration issues (e.g., frequent or incomplete regen)
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the injector wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the injector's resistance with a multimeter (typically 0.5-2 ohms). Compare to manufacturer specs.
Step 4: Check for voltage and ground at the injector connector with the ignition on. If missing, trace circuit back to PCM.
Step 5: If wiring and injector test OK, suspect a faulty PCM; perform a PCM relay and power check.
4. 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 DPF clogging, increased emissions, and potential engine damage. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, but can be higher if the injector or PCM needs replacement. Parts alone for the injector can cost $100-$300.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.