Do NOT keep buying parts in the ‘hope’ that the problem will go away.
Firstly this is a really expensive waste.
Secondly, if you did not correctly identify the root cause then you have no idea if you have properly fixed the problem or just temporarily masked it.
When we hear stories of ‘its been fixed five times and the fault keeps coming back’, that tells us that the fault was never ever actually fixed, just masked.
So what do you do, well first of all keep calm, panicking will always make things worse!
1. Properly identify what the symptoms are. Be objective, not subjective. If a noise seems to be coming from the right rear wheel then get someone else to sit in the back and verify that it really does, noises have a habit of travelling along hard surfaces and appearing somewhere else!
2. If appropriate use a diagnostic tool. But CAUTION! The tool will give you clues dressed up as facts, don’t take everything it says literally. Every fault code needs to be correctly interpreted, if in doubt ask someone who is familiar with that type of vehicle.
3. Research common causes, the internet can be a great resource as well as having many misleading or false bits of information, so again don’t take anything too literally, it’s all clues. Type in any fault codes and the symptoms you have accurately found. Get several results from different sites and see if there is consensus. Do NOT use AI.
4. Given the probable cause of the fault return to the car and see if this is the case, we are looking for evidence to verify the diagnosis. For instance if you suspect a faulty ABS sensor then back probe the sensor, ignition turned on and spin the wheel to see the pulses on an oscilloscope. If you don’t have the right kit to do the test, ask about and you will probably find someone nearby who can help.
5. Now you have proved the cause of the fault either repair the part or fit a new one. But we’re not done just yet!
6. Verify the repair has worked, test signals and performance. Test drives are essential and then recheck for faults.
Common mistakes:
Reading a fault code and replacing a part without checking its function, wasteful and often ineffective.
Replacing sensors or other electrical parts before checking wiring and connectors is a bad idea. Over 90% of electrical faults are connectors, which can sometimes be fixed by cleaning and applying electrical gel/paste to prevent corrosion.
Not cleaning surfaces before fitting mechanical parts, this often leads to problems a few months later, such as gaskets leaking or brake discs vibrating.
Brake judder caused by fitting new disks to unclean hub surfaces. If the brakes keep warping then they are not being fitted right, or there is a parts supply defect.
Mixing up adjustment for failure. Sometimes things just need adjusting, not replacing, such as handbrakes.
There’s loads more..
But that’s a very brief guide to the diagnostic procedure, basically get the facts straight first and do the job once properly.
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