P2153

Code

Generic P — Powertrain

Fuel Injector Group C Supply Voltage Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 49 RU: 26

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Page language: EN

Causes

Blown fuse or faulty relay for injector/fuel system supply
Open or high-resistance wiring in injector group C supply or ground
Short to ground on the injector supply circuit
Corroded, damaged, or disconnected injector harness connector(s)
Faulty fuel injectors dragging the supply down (internal short)
Faulty injector driver or power stage inside the ECM/PCM

Symptoms

MIL (Check Engine Light) illuminated
Rough idle, stumbling or engine misfire affecting cylinders in group C
Hard starting or no-start condition (if supply is severely low)
Reduced engine power or limp-home behavior
Poor fuel economy and increased emissions
Intermittent faults or codes that clear and return

What to check

Retrieve freeze-frame and all stored/related DTCs with a scan tool
Check battery voltage and charging system (engine off and running)
Inspect fuses and relays for the injector/fuel system circuit
Visually inspect wiring and connectors for group C injectors for damage, corrosion or loose pins
Backprobe injector group C supply connector and measure voltage with key ON (engine off)
Disconnect group C injectors and re-check supply voltage to isolate short in injectors vs wiring/ECM

Signal parameters

Expected injector supply voltage ≈ battery voltage with key ON — typically ~11–14.5 V (verify against vehicle spec)
Injector driver behavior: ECM switches injectors to ground; pulse width varies with load — verify pulse presence with scope or scan tool
Injector coil resistance: varies by design and vehicle — consult OEM; typical ranges (varies widely) can be roughly 1–20 Ω (low-impedance) or 12–60 Ω (high-impedance); compare each injector to spec
No sustained low-voltage condition at the group supply pin when injectors disconnected (should see near-battery voltage)

Diagnostic algorithm

Read and record all DTCs and freeze-frame data. Note which cylinders or injectors are in group C for the specific vehicle.
Verify battery state of charge and charging system output; ensure voltage is >12.4 V (engine off) and charging when running.
Inspect related fuses and relays; replace any blown fuses and swap or bench-test suspect relays.
With key ON (engine off), backprobe the injector group C supply pin and verify supply voltage at the harness connector. If voltage is low, proceed to step 6.
Disconnect group C injectors (unplug harness). Re-measure supply voltage at the harness connector: if voltage returns to battery voltage, suspect one or more shorted/failed injectors. If voltage remains low, suspect wiring/relay/fuse/ECM.
Inspect wiring from fuse/relay/ECM to group C connectors for damage, pin corrosion, or shorts to ground. Use a wiring diagram to identify circuits and test continuity to ground and to the power source.
Measure individual injector resistances and compare to OEM specification. Replace any injector out of spec or showing internal short.
If wiring and injectors check good, use a lab scope to view injector driver waveforms at the injector side while cranking/running to confirm driver switching and look for excessive load or abnormal waveform shape.
If scope and bench tests point to a failed injector driver or power stage inside the ECM, confirm by following manufacturer ECM diagnostic procedures before replacing ECM.
Clear codes and perform a road test or operational test to confirm repair. Monitor for reoccurrence.