Fault code P0261 – a step-by-step guide to diagnosing and fixing it

Error code P0261 is displayed and the check engine light is on - what does this mean?

The OBD-II system detects a fault in the electrical circuit of the fuel injector of cylinder 1 (low current). This DTC is set when the engine control unit detects that the electrical current to the first injector is below the expected value or is completely interrupted.

What can cause this fault code?

• Defective fuel injector cylinder 1
• Damaged or corroded cable to the injector
• Loose or corroded plug connections
• Defective engine control unit (ECM/PCM)
• Blown fuse in the injector circuit
• Short circuit in the wiring
• Defective injector relay
• Oxidized or dirty contacts in the connector

What symptoms occur in parallel with fault code P0261?

• Engine running unevenly: The engine runs unevenly or jerks when idling
• Loss of power: Noticeable reduction in engine power
• Increased fuel consumption: Deteriorated fuel efficiency
• Starting problems: Difficult starting or longer starting times
• Misfiring: Irregular combustion in cylinder 1
• Black smoke: Dark exhaust fumes from the exhaust
• Check engine light: Permanently lit check engine light

How to fix the problem of error code P0261?

• The repair requires a systematic diagnosis of the injector circuit of cylinder 1.
• Check the injector connector and wiring: Disconnect plug connection on injector 1, check for corrosion and damage, clean contacts and check cables for breaks or chafing points
• Injector resistance measurement: Measure the resistance of the injector with a multimeter (typically 12-16 ohms), replace the injector if there are deviations
• Test the power supply and ground: Switch on the ignition and measure the voltage at the injector plug (should be 12V), check the ground cable for continuity
• Replace injector: Replace defective fuel injector of cylinder 1 with a new or overhauled part, replacing seals at the same time
• Check fuses and relays: Check injector fuse in fuse box and replace if necessary, replace and test injector relay
• Diagnose the engine control unit: For all other intact components, have the ECM/PCM checked for internal defects and replace if necessary