P2157

Code

Generic P — Powertrain

Fuel Injector Group D Supply Voltage Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 38 RU: 25

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Completed

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Page language: EN

Causes

Short to battery/constant voltage on the injector group power feed
Faulty wiring or damaged insulation in the injector group harness
Poor or corroded connector terminals at injector group or power source
Failed fuse or relay supplying injector group (stuck closed or shorted)
Faulty Engine Control Module (ECM) power transistor or voltage sensing
Aftermarket accessories or improper repairs that tied power to the feed

Symptoms

Check Engine Light (MIL) illuminated
Stored P2157 (or related) DTC(s) and possible multiple injector-related codes
Hard starting or extended cranking
Rough idle, misfire, or reduced engine power under load
Intermittent driveability problems or engine stall (if group feed becomes unstable)
Possible electrical odors or visible wiring damage in engine bay

What to check

Retrieve active and pending codes and freeze-frame data with a scan tool; record all related codes and engine conditions
Visually inspect injector group wiring harness, connectors, and insulation for damage, pin corrosion, pushed-out pins, or melted areas
Check fuses and relays for the injector supply circuit; inspect for signs of overheating or aftermarket bypasses
Measure battery voltage and charging system voltage to confirm there is no overcharging (>15.5 V)
Backprobe the injector group power feed connector with a digital multimeter (DMM) with key ON, engine OFF to read supply voltage
Inspect ground points related to the engine and ECM for tightness and corrosion

Signal parameters

Expected injector group supply voltage (key ON, engine OFF): approximately battery voltage ≈ 11–14.5 V
Expected supply voltage (engine running): approximately battery/alternator voltage ≈ 13–14.5 V (unless charging system over-voltage)
High condition: measured voltage consistently above normal charging range (typically >15–16 V) or spurious high readings reported by ECM
Injector control: injectors are typically supplied with constant battery voltage and switched to ground by the ECM — control pulses are ground-side PWM signals (pulse width depends on load)

Diagnostic algorithm

Confirm code and context: Read freeze-frame and pending codes. Note battery voltage and engine state when the fault occurred.
Visual inspection: With the battery disconnected, inspect the injector group harness, connectors, and fuse/relay area for damage, corrosion, melted insulation, or aftermarket splices.
Check fuses/relays: Verify the fuse(s) and relay(s) feeding the injector group. Replace or swap with known-good relay of same type if suspect.
Verify supply voltage: Reconnect battery. With key ON (engine OFF), backprobe the injector group power feed at the harness connector and measure DC voltage. It should match battery voltage. If it is excessively high, check charging system voltage at battery.
Check for short to battery: With ignition OFF and battery disconnected, use an ohmmeter to check continuity between the injector group power feed and battery positive (should show open when no power source present). If there is continuity, trace harness for direct short or bypass splice.
Isolation test: Disconnect the injector group connector and clear codes. Start engine or cycle ignition to see if code returns. If the code disappears with connector disconnected, suspect circuit downstream (injectors or harness); if it remains, suspect power feed or ECM.

Likely causes

Short to B+ in the injector group harness (pin-to-pin or pin-to-chassis with power present)
Corroded/loose power connector at injector group or fuse/relay panel causing intermittent high readings
Failed power supply circuitry inside the ECM introducing high voltage to the feed
Blown or modified wiring that bypasses normal fuse/relay protection

Fault status

⚠️ Status

ECM detected abnormally high voltage on Fuel Injector Group D supply circuit. Check wiring, connectors, power fuses/relays, charging system and ECM supply circuitry.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours