Fuel Injector Group Supply Voltage Circuit Low
The P2156 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the supply circuit for a group of fuel injectors. This can be caused by a faulty injector driver, wiring issues, or a failing PCM. The injector group supply voltage is critical for proper fuel delivery; low voltage can lead to lean misfires, reduced power, and increased emissions.
01. Most Common Causes
- Faulty fuel injector driver module
- Open or shorted wiring in injector supply circuit
- Corroded or loose connector at injector or PCM
- Failed PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Reduced engine power and poor acceleration
- Increased fuel consumption
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect injector wiring and connectors for damage or corrosion.
Step 3: Measure voltage at injector group supply circuit with a multimeter (should be near battery voltage with key on).
Step 4: Check continuity and resistance in the circuit; repair or replace as needed.
Step 5: Test injector driver module or PCM if circuit is intact.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Low injector voltage can cause misfires and potential catalytic converter damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Repair costs vary from $150 for wiring repairs to $400 or more for replacing an injector driver module or PCM.