Fuel Injector Group Supply Voltage Circuit High
The P2157 code indicates that the powertrain control module (PCM) has detected a voltage level in the fuel injector group supply circuit that is higher than the specified range. This circuit provides power to a group of fuel injectors, and an overvoltage condition can result from a faulty voltage regulator, a short to voltage in the wiring, or a malfunctioning PCM. High voltage can cause injectors to stay open longer than intended, leading to an overly rich fuel mixture, reduced fuel economy, and potential engine damage.
1. Most Common Causes
- Faulty voltage regulator or alternator overcharging
- Short to battery voltage in the injector supply circuit wiring
- Corroded or damaged connector at the injector group
- Failed PCM (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine running rich (black smoke from exhaust)
- Poor fuel economy
- Rough idle or misfire
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P2157 and check for other codes.
Step 2: Visually inspect the fuel injector wiring and connectors for damage, corrosion, or shorts.
Step 3: Measure voltage at the injector group supply circuit with a multimeter; compare to manufacturer specs (typically 12V with engine running).
Step 4: Test the alternator output voltage to ensure it is within range (13.5-14.5V).
Step 5: If voltage is high, isolate the circuit by disconnecting the injector group and re-testing to pinpoint the source.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P2157 as high voltage can damage fuel injectors and the catalytic converter. Have the vehicle inspected promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on the cause. Wiring repairs are cheaper, while replacing the PCM can be more expensive.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.