P0262: Cylinder 1 Injector Circuit High
Diagnostic Trouble Code (DTC) P0262 indicates that the Engine Control Module (ECM/PCM) has detected that the electrical voltage in the fuel injector control circuit for Cylinder 1 has exceeded the calibrated high electrical threshold, or that the low-side driver circuit is shorted to a positive voltage source (such as 12V battery power or the 80V-200V high-voltage boost rail). Under normal conditions, the low-side control line is switched to ground only during injection firing; during rest periods, voltage is controlled by an internal pull-up circuit. If this wire contacts a continuous high voltage, or if the internal inductive kickback clamping diode fails, DTC P0262 is stored and Cylinder 1 is deactivated.
🚗 Operational Safety, Typical Repair Costs & Diagnostic Verification
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🚦 Driving Safety & Operational Risk
Immediate mechanical assessment and tow requirementsCylinder 1 Injector Circuit High - Continuous High-Voltage Short or Driver Stage Lockup
Cylinder 1 injector circuit is detecting abnormal high voltage (short to battery or internal boost rail). This can force the injector to stay physically open, hydro-locking the engine.
MECHANICAL HAZARDS & ENGINE RISK IF DRIVEN:Stuck-open injector can melt the piston crown, bend connecting rods, or induce diesel runaway. - 02
💰 Typical Workshop Repair Budget
Expected parts replacement and garage labor cost tiersMinor DIY / Filter Purge$45 - $110 (Harness Short-to-Power Inspection & Repair)Sensor cleaning, fuel filter renewal, fuse replacement, or harness contact cleaning.
Sensor / Valve Replacement$240 - $550 (Replacement of Defective Cylinder 1 Injector Unit)Single component fix (e.g. pressure regulator valve, inlet metering unit, or reconditioned injector).
Major Overhaul / Pump & Injectors$850 - $2,200 (ECU Mainboard Replacement or Engine Teardown for Hydro-lock Damage)High-pressure injection pump overhaul, new OEM injector set, or DPF assembly replacement.
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🧰 Initial Visual & Physical Verifications
5-minute zero-tool garage triage steps before calling a workshop11. Check engine oil level immediately: If oil level is rising or smells strongly of diesel fuel, do not crank the engine (injector leaking).22. Disconnect Cylinder 1 injector and verify whether short-to-power persists on harness connector with KOEO.33. Inspect harness loom near exhaust heat shield for melted insulation bridging wires together. - 04
🛡️ Diagnostic Verification & Mechanic Shield
Exact questions to ask your technician to prevent unnecessary parts replacement""Check oil level on dipstick and perform cylinder bore scope inspection before attempting repeated engine starts.""
""Measure voltage on injector signal wire with key on; it should not see continuous 12V or 80V rail voltage without active pulse.""
""Ensure compression test is performed if cylinder was filled with liquid diesel to confirm connecting rod straightness.""
Technical Note: Read these technical questions to your mechanic before approving expensive parts replacements:
30-Second Workshop Triage
- Violent engine shaking, severe shudder, and continuous single-cylinder misfire under all operating conditions
- Significant loss of vehicle acceleration, sluggish throttle response, and inability to maintain highway cruising speeds
- Illuminated Check Engine Light (MIL) accompanied by flashing glow plug warning light and ESP/traction warning
- Cylinder 1 injector control wire shorted to 12V battery power or an adjacent energized wire in the wiring harness loom
- Cylinder 1 injector high-side driver wire shorted to an un-switched 12V power supply due to harness melted insulation
- Internal short circuit inside the Cylinder 1 fuel injector coil winding bridging power to the control terminal
Connect scan tool live telemetry: compare Target Fuel Rail Pressure vs Actual Rail Pressure and log metering valve command PWM duty cycle during idle and road load.
Expensive Diagnostic Pitfall & Technical Reality
P0262 proves the engine control module (ECM) internal driver stage has blown and the ECM must be replaced and reprogrammed ($1,500 - $2,800).
P0262 indicates that the Cylinder 1 injector low-side control wire is shorted to battery positive voltage (+12V or +80V boost rail), or the internal solenoid coil resistance has open-circuited. The ECM's diagnostic driver senses that the voltage does not drop to near-zero when the driver transistor turns ON. In over 80% of verified cases, the ECM is completely unharmed. The true culprit is a broken internal solenoid coil bonding wire inside the injector head (reading OL infinity on a multimeter) or a pinched wire harness shorting against an adjacent +12V power supply wire.
Unnecessarily condemning a $2,000 ECM vs measuring coil resistance with a $20 multimeter to pinpoint an open injector coil ($180 rebuild) or repairing pinched wiring ($15), saving over $1,800.
Most Common Engines & Fuel Injection Platforms Affected
This fault code predominantly affects the following common rail diesel platforms. Cross-reference your specific engine family below for verified factory failure modes, key sub-assembly part numbers, and dedicated repair links:
Volkswagen / Audi 2.0 TDI (EA189 / CFFB / CFGB)
Bosch EDC17 Common Rail SystemKnown Factory Failure Mode: Piezo stack degradation, injector harness terminal fretting, DPF differential pressure sensor silicone tube split.
03L130277, 0445110369, 076906051AMercedes-Benz 2.1 CDI (OM651 / OM646)
Delphi CRD2 / Bosch Common Rail InjectionKnown Factory Failure Mode: Delphi piezo to solenoid conversion wiring harness chafing, differential pressure sensor internal diaphragm drift.
A6510704987, A6510700587, A0061539528BMW 2.0d / 3.0d (N47 / N57 / M57TU2)
Bosch CRI2.5 / CRI3.0 Common RailKnown Factory Failure Mode: Injector balance drift beyond +/- 4.0 mg/stroke, glow plug control unit (BERU) power lead failure, DPF backpressure accumulation.
13537805428, 0445116024, 12217801201Ford 6.7L Powerstroke V8 Diesel
Bosch CP4.2 High-Pressure Common Rail SystemKnown Factory Failure Mode: EGR cooler carbon clogging, DEF injector white crust crystallization, fuel volume control valve harness chafing.
BC3Z-9A543-A, FC3Z-9F593-B, BC3Z-5J281-AP0201-P0204 Injector Circuit Diagnosis Guide
Workshop troubleshooting guide for OBD-II codes P0201 to P0204 (Cylinder 1-4 Injector Circuit Malfunction). Resistance test specs, harness checks, and ECU driver stage.
Control Circuit & Actuator Logic
1. Dynamic In-Demand Fuel Metering
Common rail diesel fuel injectors are driven by a sophisticated dual-switch topology inside the ECM: a shared high-side power MOSFET and an individual low-side ground-switching MOSFET. The injector coil is energized by high voltage (80V-90V solenoid, 140V-200V piezo). During normal operation, when the low-side driver opens at the end of injection, an inductive voltage spike of ~50V is generated and clamped by an internal freewheeling diode. If the low-side wire is physically shorted to constant 12V battery voltage or another energized circuit in the wiring loom, the ECM registers a continuous high-voltage condition.
2. Closed-Loop PID Deviation Monitoring
The ECM performs continuous hardware monitoring of the Cylinder 1 driver stage. If the low-side driver terminal measures constant battery voltage (>11.5 V) when the driver is commanded to pull to ground, or if voltage remains higher than calibrated diagnostic thresholds during the Key-ON static test window, DTC P0262 is flagged. To prevent the short-circuit voltage from back-feeding into the ECM internal logic boards, the ECM disables firing pulses to Cylinder 1 and initiates Limp-Home Mode.
3. Diagnostic Trap: Normally Open (NO) vs Normally Closed (NC) Valves
Continuous High-Voltage Short vs Latching Injector Hazard: If the Cylinder 1 injector circuit is shorted to a positive voltage feed while the ground side is also compromised, the solenoid coil can become continuously energized (100% duty cycle). In a diesel engine, an injector held continuously open dumps 1800 bar fuel directly into the cylinder. Within seconds, this causes hydraulic cylinder lock (Hydro-Lock) or severe piston melting. If code P0262 is detected, NEVER crank the engine until wiring harness continuity to 12V is completely isolated!
Electrical & Hydraulic Physical Benchmarks
Step-by-Step Workshop Diagnostic Protocol
Unplug Diagnostic Flip Test (Isolating Harness vs Injector)
Turn the ignition Key-ON with the engine stopped. Clear stored trouble codes. Unplug the electrical connector from the Cylinder 1 fuel injector while monitoring live scan tool codes. If code P0262 immediately clears and transforms into P0201 (Cylinder 1 Circuit Open), the wiring harness and ECM driver are 100% HEALTHY-the injector itself has an internal short circuit! If P0262 persists with the injector completely disconnected, the wiring harness is shorted to a power source.
Harness Short-to-Voltage Multimeter Audit (Key-ON Engine-OFF)
With the Cylinder 1 injector disconnected and Key-ON, measure DC voltage on both pins of the harness connector to engine battery negative. Pin 1 (High-Side Feed) should read 0.0V (or a low floating diagnostic voltage <3.0V when un-energized). Pin 2 (Low-Side Control) should read floating voltage <2.0V. If either pin reads a solid 12.0V-14.0V battery voltage with the engine stopped, that wire is shorted to a 12V power wire inside the engine harness conduit.
Precision Four-Wire Low-Resistance Coil Measurement
Using a milliohm meter or digital multimeter with lead-zeroing on the lowest ohms scale, measure resistance across the two pins of the Cylinder 1 injector: normal resistance for solenoid injectors is 0.20 Ω to 0.45 Ω @ 20°C; for piezo injectors, 180 kΩ to 220 kΩ. A reading of 0.0 Ω (dead short) or abnormal high resistance (>2.0 Ω on solenoid) confirms internal coil winding breakdown.
Harness Continuity & Wire-to-Wire Short Circuit Test
Turn Key-OFF, disconnect battery, and unplug the ECM main harness connector. Using a multimeter on ohms scale, measure resistance between the Cylinder 1 injector wires and all other pins in the engine harness connector. Resistance must be infinite (OL). If any measurable continuity (<100 kΩ) exists to another circuit, trace the harness for melted conduit caused by contact with the exhaust or turbo.
Connector Water Ingress & Terminal Arcing Inspection
Inspect the female terminal cavities of the Cylinder 1 connector for black arcing soot or green copper corrosion. Water or conductive road salt ingress can bridge the high-voltage supply pin across the plastic housing into the low-side pin, creating an artificial P0262 short-to-power condition.
Oscilloscope Waveform & Inductive Clamping Verification
Reconnect the injector and back-probe the low-side control wire with an oscilloscope. Crank the engine: verify that the low-side driver pulls the signal cleanly to ground during firing and releases cleanly with a sharp inductive flyback voltage peak clamped at ~45V-55V. If the voltage remains pinned at 12V or fails to switch, the ECM low-side driver transistor is internally shorted.
Component-Level BOM: Cylinder 1 Common Rail Injector Drive & Wiring Subsystem
Cylinder 1 Common Rail Injector Drive & Wiring Subsystem
0 445 110 369 / 0 445 116 059
High-speed electro-hydraulic fuel injector with calibrated pilot/main injection metering
1 928 498 056 / Tyco Junior Timer 2-Way
Provides positive terminal spring tension to withstand 150V injection pulse vibrations
OEM Oil-Resistant Wiring Loom (Make-specific)
Prevents 130°C hot engine oil from degrading wire insulation
Injector Solenoid & Piezo Resistance Inspector
Associated Fuel Injection Components
The following genuine OEM fuel pumps and common rail injectors are verified factory equipment for engines reporting fault protocol P0262. Cross-reference operating pressures and tightening torques before sub-assembly replacement:
0445110369BOSCH
0445110369 Injector: VW 2.0 TDI EA189 CFFB CFHC Specs
View Technical Specs & Fitment →0445116024BOSCH
BOSCH 0445116024 Common Rail Piezo Injector for BMW N47 2.0d & N57 3.0d
View Technical Specs & Fitment →095000-5880Denso
095000-5880 Denso Toyota 2KD-FTV Injector: 23670-30050 Data
View Technical Specs & Fitment →28337917Delphi
28337917 Delphi Bobcat D24 Injector: 7030364 Specs & Data
View Technical Specs & Fitment →095000-8340Denso
095000-8340 Denso Mitsubishi 4D56 HP Injector: 1465A367 Data
View Technical Specs & Fitment →0445120289Bosch
0445120289 Bosch Perkins 1104D Injector: 2645A749 Data
View Technical Specs & Fitment →Cylinder 1 Injector IMA/QR Calibration & Driver Reset Procedure
Following replacement of the Cylinder 1 fuel injector or repair of the shorted wiring harness, execute the calibration routine:
1. Enter the new 6-to-30 digit alphanumeric calibration code (IMA / QR code) stamped on the top of the new Cylinder 1 injector into the ECM via scan tool.
2. Clear all stored trouble codes and ensure battery voltage is fully charged (>12.5 V).
3. Access scan tool 'Engine Control Module' -> 'Special Functions' -> select 'Reset Injector Driver Stage Fault Memory'.
4. Start the engine and let it idle at full operating temperature (coolant >80°C) for 5 minutes without touching the accelerator.
5. The ECM will perform smooth-running control (SRC) zero-fuel calibration cycles to re-balance cylinder torque.
6. Conduct a 15-minute road test through all gear ranges, verifying smooth idle, instant throttle response, and zero pending DTCs.
Differential Diagnosis & Related Faults
Injector Circuit/Open - Cylinder 1
Companion open-circuit fault on Cylinder 1; unplugging a shorted injector will transform P0262 into P0201, confirming the injector is bad.
Cylinder 1 Injector Circuit Low
Opposite electrical failure: occurs when the injector control wire is shorted to vehicle chassis ground rather than to a positive voltage source.
Cylinder 1 Misfire Detected
Direct mechanical consequence: because the ECM disables the Cylinder 1 injector driver, Cylinder 1 fails to fire, setting misfire code P0301.
Workshop Field Case Studies
2014 Mercedes-Benz C250 CDI (W204 OM651 Delphi)(178,000 km)
Frequently Asked Technical Questions
What does engine fault code P0262 mean?
Diagnostic Trouble Code (DTC) P0262 indicates that the Engine Control Module (ECM/PCM) has detected that the electrical voltage in the fuel injector control circuit for Cylinder 1 has exceeded the calibrated high electrical threshold, or that the low-side driver circuit is shorted to a positive voltage source (such as 12V battery power or the 80V-200V high-voltage boost rail). Under normal conditions, the low-side control line is switched to ground only during injection firing; during rest periods, voltage is controlled by an internal pull-up circuit. If this wire contacts a continuous high voltage, or if the internal inductive kickback clamping diode fails, DTC P0262 is stored and Cylinder 1 is deactivated.
What are the most common symptoms of P0262?
Violent engine shaking, severe shudder, and continuous single-cylinder misfire under all operating conditions, Significant loss of vehicle acceleration, sluggish throttle response, and inability to maintain highway cruising speeds, Illuminated Check Engine Light (MIL) accompanied by flashing glow plug warning light and ESP/traction warning, Heavy puffing of white, grey, or black unburned diesel smoke from exhaust pipe during starting and acceleration, Strong, pungent odor of raw diesel fuel surrounding the vehicle exhaust and engine bay, Diagnostic scan tool live data shows Cylinder 1 contribution balance pegged at maximum positive fuel trim (+4.5 to +6.0 mg/stroke).
What causes P0262 on a diesel engine?
Cylinder 1 injector control wire shorted to 12V battery power or an adjacent energized wire in the wiring harness loom; Cylinder 1 injector high-side driver wire shorted to an un-switched 12V power supply due to harness melted insulation; Internal short circuit inside the Cylinder 1 fuel injector coil winding bridging power to the control terminal; Damaged, shorted, or blown output driver MOSFET transistor inside the Engine Control Module (ECM); Water, engine oil, or road salt contamination inside the main engine wiring bulkhead connector bridging 12V to the injector pin; Aftermarket performance tuning box or piggyback wiring harness shorting internal injector driver tracks.
Is it safe to drive with code P0262 active?
🟡 Caution: Limp Mode Active / Service Soon
How much does it cost to fix fault code P0262?
Typical repair costs for fault code P0262 depend on the underlying root cause and diagnostic tier: Level 1 (Minor / Maintenance): $45 - $110 (Harness Short-to-Power Inspection & Repair) (Sensor cleaning, fuel filter renewal, fuse replacement, or harness contact cleaning.); Level 2 (Component Replacement): $240 - $550 (Replacement of Defective Cylinder 1 Injector Unit) (Single component fix (e.g. pressure regulator valve, inlet metering unit, or reconditioned injector).); Level 3 (Major Sub-Assembly): $850 - $2,200 (ECU Mainboard Replacement or Engine Teardown for Hydro-lock Damage) (High-pressure injection pump overhaul, new OEM injector set, or DPF assembly replacement.). Independent workshop benchmark rates. Data indicates over 70% of occurrences are resolved within Level 1 or Level 2 without replacing entire sub-assemblies.
What does 'Circuit High' mean on a fuel injector circuit?
In an injector circuit, 'Circuit High' means the ECM has detected voltage on the low-side control wire that is higher than it should be. Normally, this wire is either floating at a low diagnostic voltage or pulled to ground (0V) to fire the injector. If this wire contacts 12V battery power or high voltage from another circuit in the harness, the ECM flags code P0262.
Can code P0262 cause the engine to hydro-lock?
Yes, in severe failure modes where the injector coil is shorted to power while the ground side is completed, the injector can be held continuously energized (wide open). Because the common rail stores diesel at 1800 bar, the injector will pump liquid diesel into Cylinder 1 at high volume. If the cylinder fills with liquid diesel, the engine will suffer hydraulic lock upon cranking, bending connecting rods and destroying the engine.
How do I diagnose whether P0262 is caused by a bad injector or bad wiring?
Unplug the Cylinder 1 injector connector. Turn Key-ON and check the diagnostic codes with your scan tool. If P0262 disappears and changes to P0201 (Injector Circuit Open), the wiring harness and ECM are 100% fine; the short was inside the injector coil, and replacing the injector will fix the vehicle. If P0262 remains active with the injector completely unplugged, the wiring harness wire is shorted to a 12V power line.