P1202

Code

Other P — Powertrain

Injector Circuit Open / Shorted - Cylinder #2

Brand: Other

Type: P — Powertrain

Views: UK: 44 EN: 104 RU: 61

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Page language: EN

Causes

Broken or chafed wiring in injector harness to cylinder #2
Corroded, loose or damaged injector connector/pins
Failed fuel injector (open winding or short to ground)
Faulty injector driver inside ECM/PCM
Blown fuse or faulty power/relay feeding injectors
Water ingress or contamination at connector causing short

Symptoms

Check Engine Light illuminated with P1202 present
Engine misfire on cylinder #2, rough idle or vibration
Poor acceleration or loss of power under load
Hard starting or extended crank time
Increased fuel consumption or unburned fuel smell
Possible backfire or exhaust pop on deceleration

What to check

Scan for codes and freeze-frame data; note whether other injector or misfire codes present
Visually inspect wiring and connector at injector #2 for corrosion, pin damage, pulled wires or heat damage
Check related fuses and injector power relay
Backprobe injector connector with key ON to confirm 10–14 V supply on the battery feed circuit
Measure injector coil resistance at connector (compare to service spec or another injector)
Use a noid light or oscilloscope to verify injector pulse from ECM while cranking/running

Signal parameters

Injector supply (battery feed) typically ~10–14 V with key ON (constant feed)
Injector coil resistance: typical ranges — low impedance injectors ~1–4 Ω, high impedance ~10–20 Ω (check vehicle spec)
Injector pulse width varies with load: commonly 1–20 ms depending on RPM/load; pulse is supplied as ground-side switching by ECM
Normal injector driver circuit should show switching to ground synchronized with engine timing

Diagnostic algorithm

Retrieve DTCs and freeze-frame; note operating conditions when fault set. Check for related codes (misfire, fuel rail, ECM).
Visually inspect wiring, connectors, and harness to injector #2 for damage, corrosion, or poor repair work.
With key ON, verify battery feed voltage at the injector connector. If no feed, inspect fuses/relays and repair as needed.
Measure injector coil resistance at the connector and compare to spec or another cylinder. Replace injector if coil open or shorted.
Use a noid light or oscilloscope at the injector connector while cranking/running to confirm ECM pulse signal. No pulse suggests driver or wiring open.
Perform continuity/resistance check between injector connector and the ECM pin to detect opens or high resistance. Check for short to ground or B+.
Wiggle test the harness and connector while monitoring engine behavior or live data to detect intermittent faults.
If the injector and wiring check good, suspect ECM driver. Confirm by substituting a known-good injector or using a bench driver tool, and consult manufacturer repair procedures before ECM replacement.
Clear codes and test drive after repairs to confirm code does not return.

Likely causes

Damaged connector or wiring harness to injector #2 (most common)
Failed injector coil (open or internal short)
Poor battery/ignition feed or relay/fuse feeding injector circuit
ECM/PCM driver failure (less common, consider after harness/injector checks)

Fault status

⚠️ Status

Manufacturer-specific code indicating the ECU detected an open or short in the fuel injector circuit for cylinder #2. The ECM has either no expected current/voltage or sees an abnormal current draw on that injector driver.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours