What does it mean?
P1201 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Cylinder 1 Fuel Injection Circuit Electrical Malfunction .
Symptoms
- Check engine light on, frequently with a cylinder 1 misfire code
- Noticeable shaking at idle and a rhythmic loss of power
- Weak acceleration and hesitation under load
- Hard starting, especially when the engine is cold
- Fuel smell from the exhaust and possible unburnt fuel odour
- Higher fuel consumption and, over time, catalytic converter damage
Likely causes
- Open or shorted winding in the cylinder 1 injector
- Injector connector loose, corroded or with a backed-out terminal
- Control wire from the module to injector 1 broken, chafed or shorted to ground or voltage
- Missing power feed to injector 1 from a blown fuse or a corroded supply splice
- Heat-damaged harness section running across the cylinder head
- Failed driver channel for cylinder 1 inside the control module
- Water or oil in the injector connector after a leaking valve cover gasket
How to fix it
- Read the codes and use live data to check whether cylinder 1 misfire counts rise together with this code
- With the ignition on, verify battery voltage at the supply pin of the injector 1 connector
- Measure the resistance of the cylinder 1 injector and compare it with the other cylinders
- Use a noid light or a scope on the control wire to see whether the module is pulsing injector 1
- Swap the connector or injector with a neighbouring cylinder where practical and see if the fault follows the part
- Inspect the connector and harness for oil contamination, corrosion and heat damage, and repair as needed
- Replace the cylinder 1 injector if it is electrically faulty, then clear codes and confirm the misfire counts return to zero