P2B04

Code

Generic P — Powertrain

Cylinder 5 Injection Pulse Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 24 RU: 20

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Page language: EN

Causes

Faulty or sticking injector at cylinder 5
Open/short or high-resistance wiring/connectors to injector 5
Poor injector ground or power supply (fused feed, relay)
Low or unstable fuel rail/rail pressure regulator
ECM/PCM injector driver fault or software bug
Fuel contamination or clogged injector nozzle

Symptoms

Malfunction Indicator Lamp (MIL/Check Engine) illuminated
Rough idle or vibration, especially at low speed
Loss of power or poor acceleration
Single-cylinder misfire symptoms, possible P0305 stored
Poor fuel economy and increased exhaust smoke (diesel) or emissions
Intermittent drivability issues that may improve after restart

What to check

Retrieve freeze frame and live data: commanded vs measured injector parameters and any related codes
Inspect wiring harness and connector at injector 5 for corrosion, damage, pins pushed out or poor contact
Measure injector 5 resistance with multimeter and compare to specification
Backprobe injector connector while cranking/running to confirm pulse signal and supply voltage
Check fuel rail pressure (static and during cranking/running) against spec
Perform a cylinder balance or misfire counter check to isolate cylinder 5 contribution

Signal parameters

Commanded injector pulse width (ms) — varies with load, RPM; idle commonly ~1–4 ms, under load often 4–12 ms (vehicle-dependent)
Measured injector pulse/current (A) or current waveform — should match command profile and peak current specs
Injector coil resistance (Ω) — compare to manufacturer spec (typical small gasoline injectors ~1–16 Ω; common-rail diesel solenoids vary widely)
Fuel rail pressure (kPa or psi) — must be within manufacturer range during idle and under load
Battery/charging voltage (V) — typically 12–14.5 V during operation
Engine speed (RPM) and load (%) — used to correlate expected pulse widths

Diagnostic algorithm

Connect a professional scan tool. Record code P2B04, freeze frame data and any additional codes. Note engine conditions when code set (RPM, load, temperature, fuel pressure).
Perform a visual inspection of wiring and connector at cylinder 5 injector. Repair any damaged wires, corroded terminals or poor grounds.
With ignition off, measure injector coil resistance at the connector and compare to spec. Replace injector if out of range or open/shorted.
Backprobe the injector connector with a scope or oscilloscope while cranking/running. Verify presence of proper supply voltage and correct pulse waveform (timing, duration and amplitude). Look for missing pulses, truncated pulses or excessive noise.
Check battery/charging system voltage under load; low voltage can distort injector pulses. Repair charging/battery issues before further testing.
Check fuel rail pressure (static and dynamic). Repair fuel supply/pressure regulator or pump if pressure is low or unstable.
If electrical checks look good, swap injector 5 with another cylinder’s injector. If the code or symptom follows the injector, replace the injector. If it remains on cylinder 5, suspect wiring/ECM.
If swap does not isolate, perform a cylinder compression or leak-down test to rule out mechanical causes on cylinder 5.
If wiring and injector bench tests are good, inspect/diagnose the injector driver circuit in the ECM. Check ECM power/grounds and consider reflash or replacement only after confirmation.
After repairs, clear the code and road test to verify repair. Re-scan and confirm no return of P2B04 and that driveability is restored.

Likely causes

Injector 5 electrical fault (connector corrosion, broken wire, high resistance)
Failed injector (electrically open, shorted, clogged, or mechanically sticking)
Low fuel rail pressure or fuel delivery issue
Defective injector driver circuit in ECM
Loose/poor battery/ground affecting injector driver/current sensing

Fault status

⚠️ Status

Cylinder 5 injection pulse performance out of range. Inspect injector 5, its wiring, fuel pressure and ECM injector driver. This is a diagnostic fault indicator; further testing required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours