Land Rover Discovery 4 MOT Failures: Common Issues & Parts Guide (L319, 2009–2016)

The Discovery 4 arrived in late 2009 as a substantial upgrade to the Discovery 3 — same L319 platform, but with the new 3.0-litre TDV6/SDV6 diesel replacing the troublesome 2.7, revised electronics, and an updated interior. The 5.0-litre V8 petrol was available but rare in the UK. The D4 addressed many of the D3's worst weaknesses, and the data shows it: a significantly better pass rate, lower mileage, and fewer structural issues. Based on DVSA anonymised data from 51,802 real MOT tests, here's what's failing.

Discovery 4 MOT Pass Rate

The D4 holds a 79.0% MOT pass rate — 2.3 percentage points above the UK average of 76.7%. That's a 9-point improvement over the Discovery 3's 70.0% — a major step forward, though still below most Jaguars. The improvement is consistent across model years, with the later cars benefiting from ongoing refinements.

The median mileage at MOT is 105,631 miles — 45,000 miles lower than the D3's 151,000, but still high by any measure. These are working vehicles. The severity split is 81.6% major / 18.4% dangerous.

With 25,347 failure items from 51,802 tests, the D4 averages roughly one failure item for every two tests — a marked improvement over the D3's greater-than-one-per-test average, but still a lot of parts demand.

1. Brakes — 26.2% of All Failures

Brakes have overtaken suspension as the #1 failure category on the D4, accounting for 26.2% of all failure items (6,636 items). Brake corrosion remains a major theme.

What Fails

• Brake pipe damaged or excessively corroded — 2,127 failures (the #2 individual item — still massive)
• Brake lining/pad worn below 1.5mm — 1,186 failures
• Brake hose ferrule excessively corroded — 525 failures
• Brake performance unable to be tested — 319 failures
• Brake binding — 307 failures
• Parking brake efficiency below 50% — 303 failures
• Parking brake control defective — 257 failures
• Brake disc significantly worn — 271 failures

The corroded brake pipe count at 2,127 is staggering — 1 in 24 D4s tested fails on this alone. Combined with hose ferrule corrosion at 525, that's 2,652 corrosion failures in the braking system. The parking brake failures (560 combined) confirm this remains a D4 weakness — the electronic parking brake actuators and caliper mechanisms corrode and seize.

What You Need

Tip: Brake pipe corrosion is the D4's biggest single MOT risk. Replace the steel lines with Cunifer (copper-nickel) — it's corrosion-resistant and a permanent fix. Inspect the entire brake system annually, and don't wait for the MOT to find a corroded pipe — a burst brake line is a life-threatening failure.

2. Suspension — 23.8% of Failures

Suspension remains the second-largest failure category at 23.8% (6,029 items), with the same dominant failure as the D3.

What Fails

• Suspension pin, bush or joint excessively worn — 5,015 failures (the #1 individual item — 19.8% of ALL failure items)
• Wheel bearing with excessive play — 403 failures
• Suspension joint dust cover deteriorated — 307 failures

The bush/joint wear count at 5,015 is even higher in absolute terms than the D3's 5,562, despite fewer total failure items — it's a bigger share of the total at 19.8%. At 105,000 miles median mileage, the same independent suspension system is wearing through bushes and joints. The wheel bearing count at 403 is also notable.

What You Need

Tip: As with the D3, a full suspension rebuild is more economical than piecemeal replacement. Replace all arms, bushes, and ball joints on the affected axle in one session — labour is the expensive part, and by this mileage everything on that axle will need doing within months anyway.

3. Tyres & Wheels — 16.3% of Failures

Tyres account for 16.3% of failure items (4,142 items).

What Fails

• Tyre seriously damaged — 1,382 failures (the #3 individual item)
• Tyre tread depth non-compliant — 817 failures
• Tyre cords visible or damaged — 797 failures

The D4 runs large, heavy tyres — typically 255/55 R19 or 255/60 R18 — and at over 2.5 tonnes kerb weight, it wears them faster than any Jaguar. Worn suspension bushes exacerbate tyre wear by throwing alignment out.

What You Need

4. Driveline — CV Joints, Propshaft & Bearings

The D4's complex four-wheel-drive system generates significant parts demand that doesn't fit neatly into standard MOT categories.

What Fails

• Transmission shaft bearing excessively worn — 1,011 failures (the #5 individual item)
• CV joint boot deteriorated — 692 failures
• Flexible coupling deteriorated — 220 failures

The transmission bearing count at 1,011 — 1 in 51 cars tested — is a standout. The two-piece propshaft's centre bearing is the usual culprit, and it's a known D4 weakness. The CV boot count at 692 is also high.

What You Need

5. Lamps & Lighting — 11.4% of Failures

Lighting accounts for 11.4% of failure items (2,883 items).

What Fails

• Rear registration plate lamp inoperative — 883 failures (the #6 individual item)
• Headlamp or light source inoperative — 554 failures
• Headlamp aim outside limits — 326 failures
• Lamp inoperative — 323 failures

The number plate lamp at 883 — 1 in 59 cars — is the dominant lighting failure, a persistent weak spot shared with the D3. The headlamp count at 554 is also high, reflecting failed bulbs, corroded connectors, and moisture ingress.

What You Need

Tip: Check every light before the MOT. The rear clusters are prone to water ingress — clean the connectors and apply dielectric grease. LED number plate light replacements (E-marked) last far longer than the OEM bulbs.

6. Visibility — 3.5% of Failures

Visibility issues account for 3.5% of failure items (889 items).

What Fails

• Wiper blade not clearing windscreen — 486 failures
• Windscreen washers non-functional — 335 failures

What You Need

7. Emissions & Exhaust — 2.5% of Failures

Emissions account for 2.5% of failure items (642 items).

What Fails

• Engine MIL illuminated — 424 failures

The MIL count at 424 — 1 in 122 cars — is the main emissions failure. On the 3.0 TDV6/SDV6, common triggers are DPF regeneration failures, EGR valve clogging, and turbo issues.

What You Need

8. Bonnet Latch — A D4-Specific Issue

A notable entry at #24 in the failure list: bonnet that cannot be safely secured — 221 failures. The D4's bonnet latch mechanism wears and corrodes, allowing the bonnet to pop open while driving. This is a known D4 issue — the striker and latch should be lubricated at every service and replaced preventatively if worn.

Beyond the MOT: Major Discovery 4 Faults That Drive Workshop Visits

Air Suspension Failure

Standard on most D4s. The same system as the D3 — air springs perish, the compressor wears out, the valve block leaks, and the height sensors corrode. Many owners convert to coil springs. The D4's updated software handles suspension faults slightly better, but the hardware is essentially the same.

Crankshaft Failure (3.0 TDV6/SDV6)

The most serious fault on the D4. The 3.0 V6 diesel can suffer catastrophic crankshaft failure — the same issue as the Jaguar XF and XJ with this engine. Symptoms include oil pressure warnings and bottom-end knocking. The engine is beyond economical repair. Regular oil changes with the correct specification are essential, and any oil pressure warning should be treated as an emergency.

Timing Chain Stretch (3.0 TDV6/SDV6)

The 3.0 diesel's timing chain stretches over time, retarding timing and causing rough running, poor fuel economy, and eventually an MIL failure. Unlike the earlier 2.7, the 3.0's chain is marginally more accessible, but it's still a major job. Cold-start rattle is the early warning sign.

Propshaft Centre Bearing

The two-piece propshaft's centre bearing is a known D4 weakness — a rumble or vibration at speed is the early sign. If ignored, the bearing disintegrates and the propshaft drops, potentially damaging the tunnel and underfloor components. A relatively straightforward repair if caught early.

Injector Failure (3.0 TDV6/SDV6)

Diesel injector leaks cause rough running, white smoke, and diesel knock. At this mileage, injector seals (fire rings) fail, allowing compression gases past. A hissing noise and black soot around the injector base are the telltale signs.

Gearbox Issues (ZF 8HP)

The D4 switched from the ZF 6-speed to the 8HP from 2012. Both develop shifting issues — the 8HP typically from degraded fluid, the earlier 6-speed from mechatronic unit wear. Fluid changes every 60,000 miles are recommended for both.

Sunroof Drain Blockage

The same issue as the D3 — blocked sunroof drains flood the cabin and damage the BCM under the driver's seat. Regular drain clearing is essential preventative maintenance.

Discovery 4 MOT Failure Summary — At a Glance

D4 vs D3: How Does It Compare?

The D4 is clearly the better car — structural corrosion has dropped from 5.2% to 0.9%, the pass rate is 9 points higher, and the failure-items-per-test ratio has halved. But suspension bush wear and brake pipe corrosion remain the two dominant failure modes.

Keeping Your Discovery 4 on the Road

The D4 is a genuine improvement over the D3 — better engine, better electronics, much less structural corrosion, and a pass rate that sits above the UK average. At the prices they've now reached, they're remarkable value for a full-size seven-seat 4x4.

The two non-negotiable maintenance items are brake pipe inspection (replace with Cunifer before they corrode through) and suspension bushes (budget for a full rebuild at 80,000–100,000 miles). Beyond the MOT, watch the crankshaft, timing chain, and propshaft centre bearing — catching these early is the difference between a fix and a write-off.

Browse all Discovery 4 / LR4 (2009–2016) parts at myton.parts

We stock genuine, OEM, and aftermarket parts with next-day UK delivery available.

Service & Maintenance Parts

Regular servicing is critical — oil quality directly affects crankshaft and timing chain longevity on the 3.0 diesel. Gearbox fluid changes every 60,000 miles will extend gearbox life significantly.

Data sourced from DVSA anonymised MOT test results (2024 test year, 51,802 tests on Discovery 4/LR4 models with first use dates 2010–2016). 25,347 individual failure items analysed. Specialist fault data from K Motors, Topgear Tuning, and Land Rover workshop reporting.