P1299

Code

DS P — Powertrain

Injector 4 control malfunction

Brand: DS

Type: P — Powertrain

Views: UK: 1 EN: 4 RU: 1

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Page language: EN

Causes

Open or short in injector 4 wiring harness (broken wire, chafing, rodent damage)
Corroded/poor connector or pin contact at injector or ECU
Failed injector (stuck, internal short, open coil)
Faulty injector driver in PCM/ECU
Poor power or ground to injector circuit (blown fuse, bad relay, poor ground)
Water/contamination or mechanical failure in injector

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Rough idle or vibration at idle
Misfire on cylinder 4 (engine hesitation, reduced power)
Poor fuel economy and increased emissions
Hard starting or extended crank time
Possible drivability issues under load

What to check

Read DTCs with a capable scan tool and record freeze-frame and live data
Check for related codes (misfire codes P0304, injector circuit codes) and recent adaptations
Visually inspect wiring and connector for injector 4 for damage, corrosion, pin push-out or water intrusion
With key on engine off, check for correct ignition-switched battery voltage at the injector power feed (reference OEM wiring)
Back-probe the injector control terminal while cranking/running to verify ECU command pulses (use noid light or oscilloscope)
Measure injector coil resistance with multimeter and compare to OEM specification

Signal parameters

Injector power feed: approx. battery voltage with key ON (verify OEM circuit)
Injector drive type: typically pulse-driven by ECU (low-side or high-side switching depending on vehicle)
Expected injector coil resistance: check OEM spec (typical gasoline injectors vary—confirm factory value before replacing)
Control signal: pulsed waveform during cranking/running; pulse width varies with load/engine speed (ms range), frequency increases with RPM
When commanded off: driver terminal near battery voltage (if low-side switching) or near ground (if high-side); when commanded on: driver terminal switches toward ground (low-side) or battery (high-side) — verify with service manual

Diagnostic algorithm

Connect scan tool, record P1299 and any additional codes, note freeze-frame and live data (engine rpm, load, misfire counters, fuel trims).
Attempt to reproduce while observing injector 4 status: use a noid light or oscilloscope on the injector connector control pin to confirm ECU is commanding pulses during cranking/running.
Visually inspect injector 4 connector and wiring harness for damage, corrosion, water, pin damage, or loose terminals. Repair as needed.
With key off, disconnect injector connector and measure injector coil resistance across terminals; compare to OEM specification. If open or out of spec, replace injector.
Check continuity between injector connector and ECU driver pin for opens/shorts to other circuits or ground. Wiggle harness while monitoring for intermittent faults.
Verify power feed to injectors (battery voltage) and good ground(s). Replace blown fuses or repair poor ground connections.
If wiring and injector resistance are good but no ECU command is present when expected, suspect ECU driver fault — confirm by swapping the injector connector with another cylinder (if safe and documented) and re-check codes/behavior. If fault follows the injector, replace injector; if it stays on the same cylinder, suspect wiring or ECU.
If ECU driver suspected, verify with manufacturer diagnostic procedures before replacing ECM/PCM (check for TSBs/software updates). Use oscilloscope/current clamp if needed to measure injector current draw and driver behavior.
After repairs, clear codes and perform a road/run test and re-scan to confirm P1299 does not return and engine performance is restored. Log final test results.

Likely causes

Wiring harness damage to injector 4 (opens/shorts)
Corroded/loose connector at injector 4
Failed injector coil or internal short/open
Defective PCM injector driver pin for cylinder 4

Fault status

⚠️ Status

P1299 — Injector 4 control malfunction (manufacturer‑specific). PCM detected abnormal condition on injector 4 control circuit or response.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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