Loose, corroded or damaged connector at the cylinder 3 injector; Chafed or broken wiring in the cylinder 3 injector feed or control wire, often where it flexes or touches hot or moving parts; Cylinder 3 injector with an intermittent internal winding fault; Poor connection at the engine control module connector, or terminal fretting or water ingress; Fault in the injector power supply or relevant fuse or relay connection, depending on model and engine; Internal fault in the engine control module injector driver.

P1228

Injector Circuit Cylinder 3 Intermittent.

Cadillac
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
2: AreaFuel and air metering (injector circuit)
28: FaultThe specific fault in that area

What it means

P1228 on a Cadillac means the engine control module has detected an intermittent fault in the fuel injector circuit for cylinder 3. The module monitors the injector driver circuit and saw a drop-out, open circuit or abnormal voltage or current that came and went rather than staying constant. Because the fault is intermittent, it may only appear with vibration, heat or particular driving conditions.

Symptoms

Check engine light on
Intermittent misfire or rough running on cylinder 3
Occasional hesitation or stumble under acceleration
Rough idle that comes and goes
Reduced fuel economy
Occasional hard starting or momentary engine cut-out

Possible causes

Loose, corroded or damaged connector at the cylinder 3 injectorlikely
Chafed or broken wiring in the cylinder 3 injector feed or control wire, often where it flexes or touches hot or moving partslikely
Cylinder 3 injector with an intermittent internal winding faultpossible
Poor connection at the engine control module connector, or terminal fretting or water ingresspossible
Fault in the injector power supply or relevant fuse or relay connection, depending on model and enginepossible
Internal fault in the engine control module injector driverrare

How to diagnose

Read all stored and pending codes and note the freeze frame data (engine temperature, load, speed) to see when the fault occurred.
Check for related misfire codes, especially for cylinder 3, and compare with any other injector circuit codes.
Visually inspect the cylinder 3 injector connector and wiring for damage, corrosion, loose locking tabs, oil contamination or heat damage.
With the engine running, gently wiggle the injector connector and harness while watching for a change in idle quality or misfire count on live data.
Check the injector coil resistance against the specification for the model and engine, ideally both cold and hot.
Test the injector supply voltage and ground or control signal continuity back to the control module, following the wiring diagram for that model.
Check the injector pulse with a suitable meter or scope to confirm it is consistent on cylinder 3 compared with the other cylinders.
Inspect the control module connector pins for corrosion or poor tension, and check for any relevant technical bulletins for the model.

How to fix

Clean, repair or replace the cylinder 3 injector connector and its terminals.
Repair or replace the damaged section of injector wiring, using proper soldered and sealed repairs.
Replace the cylinder 3 injector if its resistance or pulse behaviour is out of specification.
Repair the power supply, fuse or relay connection fault if one is found.
Repair the control module connector terminals, or replace and programme the module only after all wiring and injector faults are ruled out.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but an intermittent injector fault can cause misfires and the engine to cut out unexpectedly. Get it checked soon, and avoid heavy loads or long journeys, as a persistent misfire can damage the catalytic converter.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.