Common misdiagnoses that waste money
Avoid the ‘parts cannon’. These are the most common mistakes and the checks to do first.
A lot of car faults share the same symptoms. The trick is ruling out the basics before you buy expensive parts.
Here are the most common misdiagnoses we see, and what to check first.
- Replacing sensors before checking for air leaks (vacuum/boost leaks can mimic sensor faults).
- Replacing injectors before confirming fuel pressure or trims.
- Replacing a turbo for underboost when it’s a split hose or stuck wastegate actuator.
- Replacing a battery when it’s an alternator/ground/parasite drain issue.
- Replacing coils/plugs repeatedly when the real issue is compression or coolant ingress.