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Home / DTC / P02A6 — Cylinder 4 - Fuel Trim at Max Limit

P02A6 — Cylinder 4 - Fuel Trim at Max Limit

Detailed page for trouble code P02A6.

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P02A6

Generic P — Powertrain

Cylinder 4 - Fuel Trim at Max Limit

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, shorted or intermittent fuel injector circuit for cylinder 4
  • Clogged, stuck or leaking fuel injector on cylinder 4
  • Intake manifold or vacuum leak localized to cylinder 4
  • Low fuel rail pressure or fuel delivery problem
  • Faulty oxygen sensor(s) or mass air flow (MAF) sensor causing incorrect trim decisions
  • Poor electrical connection or corroded connector at the injector or harness

Symptoms

  • Check Engine Light (MIL) illuminated
  • Rough idle or vibration
  • Misfire on cylinder 4, possible stored P0304
  • Poor throttle response, hesitation or stumble
  • Reduced fuel economy
  • Failed emissions test or rich/lean O2 readings

What to check

  • Retrieve freeze frame and live data with a scan tool; note short-term and long-term fuel trims, O2 sensor behavior, and any misfire codes.
  • Visually inspect injector connector and wiring harness for damage, corrosion, or loose pins at cylinder 4.
  • Measure fuel rail pressure at idle and under load to confirm adequate supply and regulator operation.
  • Check injector electrical resistance and back-probe injector while cranking/running to confirm pulsed drive.
  • Perform a smoke test or use a vacuum gauge to check for intake manifold or vacuum leaks near cylinder 4.
  • Swap injector with another cylinder (if serviceable) and see if the problem/code follows the injector.

Signal parameters

  • Cylinder 4 fuel trim or cylinder-specific trim showing large positive or negative values (e.g., > +25% or at the monitor limit)
  • Short-term fuel trim (STFT) oscillation or STFT stuck high/low for cylinder 4
  • Bank/broad LTFT significantly out of range (e.g., P0171/P0174-style symptoms) if systemic
  • Fuel rail pressure: nominal at idle and during load (compare to OEM spec)
  • Injector pulse width for cylinder 4 compared to other cylinders (ms)
  • Upstream O2 sensor waveform slow switching or stuck lean/rich

Diagnostic algorithm

  1. Connect a capable scan tool and record freeze frame data and live PIDs: note engine speed, load, coolant temp, STFT/LTFT, cylinder trim (if available), O2 sensor status, and any misfire counters.
  2. Check for related codes (injector circuit codes P0204, misfire P0304, system lean P0171/P0174) and address their guidance.
  3. Visually inspect wiring and connector for cylinder 4 injector for damage, corrosion, loose pins, or water intrusion. Wiggle test while monitoring injector enable and trim for intermittent faults.
  4. Measure injector resistance and compare with specification. Back-probe injector connector and verify injector drive (pulse) when engine cranks/runs using an oscilloscope or noid light.
  5. Swap cylinder 4 injector with another cylinder of known-good condition; if the fault follows the injector, replace the injector.
  6. Check fuel pressure at the rail at idle and under commanded load; verify fuel delivery and regulator function. Replace fuel filter/fuel pump if pressure is low/out of spec.
  7. Perform a smoke test or spray a safe carb cleaner around intake manifold runners and gasket area near cylinder 4 to detect localized vacuum leaks (monitor fuel trims for change).
  8. Conduct compression or leak-down test on cylinder 4 to rule out mechanical causes (low compression will alter combustion and trims).
  9. Test MAF and upstream oxygen sensor(s) for correct operation; replace sensors if they provide implausible readings and other causes are ruled out.
  10. Repair identified faults (repair or replace wiring/connector, replace injector, fix vacuum leak, replace fuel pump/filter, repair mechanical issue).
  11. Clear codes, perform a road test under varying load, and re-scan to confirm the fault does not return and fuel trims normalize.
  12. Safety note: take precautions when performing fuel system and smoke tests; relieve fuel pressure and follow manufacturer safety procedures.

Likely causes

  • Cylinder 4 injector stuck closed (net lean) or stuck open (causes unusual trim behavior)
  • Damaged injector wiring or connector (intermittent open/short to ground or voltage)
  • Vacuum leak at intake runner or gasket near cylinder 4 causing localized lean
  • Restricted fuel filter or weak fuel pump causing low rail pressure under load
  • Faulty upstream O2 sensor reporting lean, causing trim to reach limit on a particular cylinder
  • Low compression or leaking valve on cylinder 4 causing miss and abnormal trim

Fault status

⚠️ Status
Cylinder 4 fuel trim reached maximum adaptive correction limit; ECM unable to correct the condition.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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Code

P02A6

LAND ROVER P — Powertrain

cylinder balance 4 - fuel compensation at maximum limit

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, shorted or intermittent fuel injector circuit for cylinder 4
  • Clogged, stuck or leaking fuel injector on cylinder 4
  • Intake manifold or vacuum leak localized to cylinder 4
  • Low fuel rail pressure or fuel delivery problem
  • Faulty oxygen sensor(s) or mass air flow (MAF) sensor causing incorrect trim decisions
  • Poor electrical connection or corroded connector at the injector or harness

Symptoms

  • Check Engine Light (MIL) illuminated
  • Rough idle or vibration
  • Misfire on cylinder 4, possible stored P0304
  • Poor throttle response, hesitation or stumble
  • Reduced fuel economy
  • Failed emissions test or rich/lean O2 readings

What to check

  • Retrieve freeze frame and live data with a scan tool; note short-term and long-term fuel trims, O2 sensor behavior, and any misfire codes.
  • Visually inspect injector connector and wiring harness for damage, corrosion, or loose pins at cylinder 4.
  • Measure fuel rail pressure at idle and under load to confirm adequate supply and regulator operation.
  • Check injector electrical resistance and back-probe injector while cranking/running to confirm pulsed drive.
  • Perform a smoke test or use a vacuum gauge to check for intake manifold or vacuum leaks near cylinder 4.
  • Swap injector with another cylinder (if serviceable) and see if the problem/code follows the injector.

Signal parameters

  • Cylinder 4 fuel trim or cylinder-specific trim showing large positive or negative values (e.g., > +25% or at the monitor limit)
  • Short-term fuel trim (STFT) oscillation or STFT stuck high/low for cylinder 4
  • Bank/broad LTFT significantly out of range (e.g., P0171/P0174-style symptoms) if systemic
  • Fuel rail pressure: nominal at idle and during load (compare to OEM spec)
  • Injector pulse width for cylinder 4 compared to other cylinders (ms)
  • Upstream O2 sensor waveform slow switching or stuck lean/rich

Diagnostic algorithm

  1. Connect a capable scan tool and record freeze frame data and live PIDs: note engine speed, load, coolant temp, STFT/LTFT, cylinder trim (if available), O2 sensor status, and any misfire counters.
  2. Check for related codes (injector circuit codes P0204, misfire P0304, system lean P0171/P0174) and address their guidance.
  3. Visually inspect wiring and connector for cylinder 4 injector for damage, corrosion, loose pins, or water intrusion. Wiggle test while monitoring injector enable and trim for intermittent faults.
  4. Measure injector resistance and compare with specification. Back-probe injector connector and verify injector drive (pulse) when engine cranks/runs using an oscilloscope or noid light.
  5. Swap cylinder 4 injector with another cylinder of known-good condition; if the fault follows the injector, replace the injector.
  6. Check fuel pressure at the rail at idle and under commanded load; verify fuel delivery and regulator function. Replace fuel filter/fuel pump if pressure is low/out of spec.
  7. Perform a smoke test or spray a safe carb cleaner around intake manifold runners and gasket area near cylinder 4 to detect localized vacuum leaks (monitor fuel trims for change).
  8. Conduct compression or leak-down test on cylinder 4 to rule out mechanical causes (low compression will alter combustion and trims).
  9. Test MAF and upstream oxygen sensor(s) for correct operation; replace sensors if they provide implausible readings and other causes are ruled out.
  10. Repair identified faults (repair or replace wiring/connector, replace injector, fix vacuum leak, replace fuel pump/filter, repair mechanical issue).
  11. Clear codes, perform a road test under varying load, and re-scan to confirm the fault does not return and fuel trims normalize.
  12. Safety note: take precautions when performing fuel system and smoke tests; relieve fuel pressure and follow manufacturer safety procedures.

Likely causes

  • Cylinder 4 injector stuck closed (net lean) or stuck open (causes unusual trim behavior)
  • Damaged injector wiring or connector (intermittent open/short to ground or voltage)
  • Vacuum leak at intake runner or gasket near cylinder 4 causing localized lean
  • Restricted fuel filter or weak fuel pump causing low rail pressure under load
  • Faulty upstream O2 sensor reporting lean, causing trim to reach limit on a particular cylinder
  • Low compression or leaking valve on cylinder 4 causing miss and abnormal trim

Fault status

⚠️ Status
Cylinder 4 fuel trim reached maximum adaptive correction limit; ECM unable to correct the condition.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

P02A0 P02A1 P02A2 P02A3 P02A4 P02A5
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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