What does it mean?
P1235 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Injection Control Circuit Commanded State to Actual State Mismatch .
Symptoms
- Check engine lamp on, sometimes only after a long drive or a heat soak
- Intermittent stall, a stumble on acceleration or a brief cut-out
- Hard starting when hot, or a longer crank than normal
- Rough running and misfire that comes and goes
- Loss of power or limp mode on some vehicles
Likely causes
- Marginal supply voltage or a weak ground that lets the circuit fall short of the commanded state
- Corroded terminals adding resistance that only shows under current
- Control relay or solenoid that operates slowly, sticks or drops out under vibration
- Chafed wiring making intermittent contact with ground or another circuit
- Component winding partially shorted, so it draws the wrong current
- Feedback wire to the module open, shorted or picking up interference
- Internal fault in the module driver or its monitoring circuit
How to fix it
- Read the freeze frame and try to reproduce the conditions in which the mismatch appeared
- Test battery, charging voltage and all engine and module grounds first
- Command the circuit on and off with the scan tool while watching the feedback parameter
- Carry out voltage drop tests on the feed, the control and the ground legs while the circuit is loaded
- Heat and wiggle-test the suspect connectors while the circuit is commanded, since this fault is often intermittent
- Measure the component resistance and its current draw and compare with specification
- Repair the circuit or renew the faulty component, then verify command and feedback track each other under load
- Suspect the module only after supply, ground, wiring and component are all proven