Code
P0066
LAND ROVER
P — Powertrain
Circuit or control circuit of injector with low air assistance
Views:
UK: 7
EN: 24
RU: 15
AI status
Completed
Completed
100%
Causes
- Open or short in the injector air‑assist wiring or connector
- Corroded, loose or damaged injector/solenoid connector pins
- Faulty injector air‑assist solenoid/actuator
- Blown fuse or faulty relay supplying the injector air‑assist circuit
- Poor ground or low battery/charging system voltage
- Faulty ECM/output driver
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Rough idle, misfire or loss of cylinder contribution
- Reduced engine power and drivability issues
- Hard starting or extended cranking
- Poor fuel economy or increased exhaust smoke
- Possible diagnostic trouble codes for related injector circuits or fuel control
What to check
- Scan for stored codes and freeze‑frame data; note which injector bank/cylinder is referenced
- Verify battery voltage and charging system health
- Visual inspection of wiring harness and connectors for damage, corrosion, or pin push‑outs
- Check fuses and relays for the fuel/injector/air‑assist circuit
- Backprobe connector at the suspect injector/solenoid; measure supply voltage, ground continuity and control signal
- Measure injector/air‑assist solenoid coil resistance with connector disconnected
Signal parameters
- Expected coil resistance (typical injector/solenoid): ~1–20 ohms (manufacturer‑specific — reference service data)
- Supply voltage to injector/solenoid: ~12 V (key ON) or battery voltage with ignition ON/engine cranking
- Control signal from ECM: pulsed ground or PWM (duty cycle and frequency vary by model)
- Ground continuity: near 0 ohms to chassis ground
- Open‑circuit indication: infinite ohms; short to ground: near 0 ohms between circuit and ground
Diagnostic algorithm
- Retrieve all DTCs and freeze‑frame data. Confirm P0066 and note related codes/cylinders.
- Visually inspect wiring and connectors for the indicated injector air‑assist circuit; repair any damage.
- Verify fuses/relays for the injector/air‑assist supply. Replace if faulty.
- With ignition OFF, disconnect the injector/air‑assist connector and measure coil resistance; compare to service spec.
- With connector back on, backprobe the supply wire with ignition ON to confirm battery voltage is present at the connector.
- Crank or run engine and use a noid light or oscilloscope on the control wire to confirm the ECM is switching the circuit (look for pulses/duty).
- Check ground circuit continuity from connector ground to chassis/ECM ground; repair if high resistance found.
- If wiring and solenoid check good but fault persists, swap a known‑good identical injector/solenoid (if available) to see if code follows component.
- If swapped component does not reproduce the fault, suspect wiring or ECM output. If fault follows component, replace the faulty injector/solenoid and clear codes.
- If ECM output driver is suspected after all harness/components verified, consult manufacturer guidance before replacing ECM (further bench testing required).
- After repairs, clear codes and perform test drive/functional checks to confirm the fault does not return.
Likely causes
- Damaged wiring harness where routed near hot/moving components
- Connector corrosion allowing high resistance or intermittent contact
- Injector air‑assist solenoid coil open or partially shorted
- Blown fuse for injector/air‑assist circuit
- ECM driver transistor failure (less common)
Fault status
Status
Injector air‑assist control circuit low/abnormal — check wiring, connectors, fuse/relay, injector air‑assist solenoid and ECM output.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email