IsItAGoodCar
Reliability Guide

Common Problems with the
2004 MG ZR

January 2004 brought a Peter Stevens facelift with new bumpers, headlights and tailgate plus a soft-touch dashboard, and added the Trophy and Trophy SE trims to the UK range.

What changed for 2004

  • •New front and rear bumpers, headlights and tailgate
  • •Revised dashboard with soft-touch buttons and new seat materials
  • •Trophy and Trophy SE trims with 16- or 17-inch alloys and a sunroof or air conditioning

Common MOT watch-outs

  • !Corrosion on rear wheel arches and sills
  • !Worn front suspension top mounts and drop links
  • !Weak parking brake efficiency from a stretched handbrake compensator
5
Known Issues
1
Serious
4
Moderate
0
Minor

All Known Issues

K-Series Head Gasket Failure (HGF)

SeriousEngine

The K-Series engine is prone to head gasket failure due to its small coolant capacity and plastic locating dowels that allow the head to shift.

Est. Repair Cost: £500–£800
Warning Signs:

Overheating, Oil in coolant / Coolant in oil, Loss of heater performance

What to Inspect:
  • Check for MLS (Multi-Layer Steel) gasket and steel dowel upgrade in history
  • Look for "mayo" under the oil filler cap
  • Verify the radiator and hoses are in good condition
Verified by IsItAGoodCar Research Team

SCU / BCU Failure (Pektron)

ModerateElectrics & Electronics

Later models (2003+) use a Pektron SCU that controls windows, fobs, and wipers. It is notorious for relay failure.

Est. Repair Cost: £150–£300
Warning Signs:

Intermittent wipers, Central locking not working on one door, Fobs not responding

What to Inspect:
  • Test all electrical functions multiple times
  • Check both key fobs
Verified by IsItAGoodCar Research Team

Worn Front Suspension

ModerateSuspension & Chassis

The front suspension bushes and ball joints wear out, leading to vague steering, knocking noises, and poor handling. This is a common MOT failure point and can be exacerbated by hard driving.

Est. Repair Cost: £100–£300
Warning Signs:

Knocking from the front end over bumps, Vague or wandering steering, Uneven front tyre wear

What to Inspect:
  • Inspect the front lower arm bushes and ball joints
  • Check for MOT advisories on suspension
Verified by IsItAGoodCar Research Team

Coil Pack Failure

ModerateEngine

The ignition coil pack is known for failing on the ZR, causing misfires, rough running, and difficulty starting.

Est. Repair Cost: £50–£150
Warning Signs:

Engine misfiring, Rough idle, Difficulty starting, Check engine light

What to Inspect:
  • Listen for misfires during test drive
  • Check for stored fault codes
Verified by IsItAGoodCar Research Team

Door Lock Failure

ModerateElectrics & Electronics

The door lock actuators, particularly on the driver's door, are known to fail, making it difficult to lock or unlock the car.

Est. Repair Cost: £80–£200
Warning Signs:

Door not locking/unlocking, Central locking intermittent, Lock clicking but not engaging

What to Inspect:
  • Test all door locks multiple times
  • Check if the driver's door lock responds
Verified by IsItAGoodCar Research Team

Buying Tips for 2004 MG ZR

  • Check the Trophy sunroof drains and the boot floor for damp
  • Confirm the facelift bumpers and headlights are intact and correctly aligned
  • Test every electrical function, especially the Pektron-controlled windows and locking
20032005
Check a 2004 MG ZR by Registration