Rear Washer Jets & MOT: Pass or Fail?

It's a common scenario for many drivers: you're preparing your car for its annual MOT, meticulously checking everything from tyres to lights, only to discover a minor issue you weren't expecting. In your case, it's the rear washer jets that have decided to take an unscheduled holiday, while everything else, including your front wipers and washers, is functioning flawlessly. The immediate question that springs to mind, quite rightly, is whether this seemingly small fault will spell disaster for your MOT certificate. Let's delve into the specifics of MOT requirements for washer systems and put your mind at ease.

When it comes to the MOT, the primary concern of the inspection is the vehicle's safety and its ability to be driven safely on public roads. This includes ensuring the driver has clear visibility at all times. This crucial aspect is where the windscreen washer and wiper system plays a vital role. The regulations are quite specific about what needs to work for the test.

The MOT and Windscreen Washer System Requirements

The MOT test has clear guidelines regarding the windscreen washer and wiper system. The key focus is on the driver's forward view. For a vehicle to pass its MOT, the windscreen washer system must be capable of cleaning the windscreen effectively to give the driver a clear view of the road ahead. This typically means:

• The washer fluid reservoir must contain fluid.
• The pump must operate to deliver fluid to the jets.
• The jets must effectively spray fluid onto the windscreen.
• The wipers must then clear the fluid, along with any dirt or debris, from the windscreen.

It's important to understand that the emphasis is overwhelmingly on the front windscreen. This is because the driver's primary line of sight and immediate safety depend on a clear view through the front.

Front vs. Rear Washer Jets: An MOT Distinction

This is where your specific query is directly addressed. The MOT test, as per the official Driver and Vehicle Standards Agency (DVSA) guidelines in the UK, primarily inspects the functionality of the front windscreen washer and wiper system. There is no specific requirement for the rear washer jet to be operational for an MOT pass. If your front washer jets are working, spraying fluid effectively onto the windscreen, and your front wipers are clearing it correctly, your car will not fail its MOT simply because the rear washer jets are not working.

While a non-functional rear washer jet is certainly an inconvenience and something you'll want to address for your own driving comfort and safety, especially in adverse weather, it is not considered a defect that would lead to an MOT failure. The MOT is a minimum safety standard test, and a rear washer isn't deemed critical for fundamental road safety in the same way the front one is.

Why the Discrepancy?

The distinction lies in the concept of 'critical safety items'. The front windscreen is paramount for safe driving. A dirty front screen significantly impairs the driver's ability to see hazards, other vehicles, and road signs, increasing the risk of accidents. While a clear rear window is beneficial for reversing and checking blind spots, it does not hold the same critical safety weight in the eyes of the MOT as the front.

Common Causes for Washer Jet Failure (Front or Rear)

Even though your rear washer jet won't fail your MOT, it's still a good idea to get it fixed. Understanding the common reasons why washer jets stop working can help you diagnose and potentially resolve the issue. These reasons apply to both front and rear systems, though the location of components might differ.

1. Blocked Jets

This is arguably the most common culprit. Over time, dirt, wax from car washes, or even dried washer fluid residue can clog the tiny nozzles of the jets. Using plain tap water instead of proper screenwash can also lead to blockages due to limescale build-up.

• Symptoms: Fluid either sprays weakly, unevenly, or not at all from the jet.
• Diagnosis/Fix: Try using a thin needle or a pin to gently clear the nozzle. Be very careful not to push the debris further in or damage the nozzle. Sometimes, a blast of compressed air (from the opposite direction if possible) can help.

2. Low or Empty Washer Fluid Reservoir

It might sound obvious, but it's often overlooked. If there's no fluid, nothing will spray. Even if there's a small amount, the pump might not be able to draw it effectively.

• Symptoms: No fluid comes out, but you might hear the pump working.
• Diagnosis/Fix: Simply top up the reservoir with good quality screenwash.

3. Faulty Washer Pump

The pump is responsible for pushing the fluid from the reservoir to the jets. If the pump fails, no fluid will be delivered.

• Symptoms: You activate the washers, but you hear no whirring sound from the pump, and no fluid comes out.
• Diagnosis/Fix: Locate the pump (usually near the reservoir). Have someone activate the washers while you listen. If there's no sound, the pump might be faulty or not receiving power. This often requires professional diagnosis and replacement.

4. Leaks in the Washer Hoses

The fluid travels from the pump to the jets via a network of rubber or plastic hoses. These hoses can crack, split, or become disconnected over time, leading to leaks.

• Symptoms: You might see fluid leaking under the car when you activate the washers, or the reservoir empties quickly without any spraying from the jets.
• Diagnosis/Fix: Visually inspect the hoses, especially where they connect to the pump, along the bonnet, and around the rear of the car for the rear washer. Look for wet spots or visible damage. Small leaks might be temporarily repaired with electrical tape, but replacement is usually the best long-term solution.

5. Electrical Issues

The washer system relies on electrical power to operate the pump. A blown fuse, a faulty relay, or damaged wiring can prevent the pump from working.

• Symptoms: No sound from the pump, no fluid, and potentially other electrical components on the same circuit might also be affected.
• Diagnosis/Fix: Check your car's fuse box (refer to your owner's manual) for the fuse related to the washer system. If it's blown, replace it with one of the correct amperage. If the fuse is fine, the issue could be with the wiring or the switch, which might require a mechanic's expertise.

Troubleshooting Your Rear Washer Jet

Since your front system is working, it's less likely to be a general electrical issue affecting the entire system. Here's a systematic approach to troubleshooting your rear washer jet:

1. Check the Reservoir Level: Ensure the washer fluid reservoir is full. Some vehicles have separate pumps or even separate reservoirs for front and rear, though this is less common.
2. Listen for the Pump: With the ignition on, activate the rear washer. Can you hear the pump whirring? If you can hear it but no fluid comes out, the issue is likely a blockage or a leak in the line to the rear. If you hear nothing, it could be the pump itself, a fuse, or wiring specific to the rear system.
3. Inspect the Rear Jet Nozzle: As mentioned, use a thin pin to gently clear any visible blockages.
4. Trace the Hose: For the rear washer, the hose typically runs from the front of the car, often along the chassis or through the cabin, to the rear tailgate. Open the tailgate and inspect the hose where it enters the tailgate and where it connects to the jet. These areas are prone to kinks or disconnections due to the constant opening and closing of the tailgate.
5. Check for Leaks: Have someone activate the rear washer while you carefully inspect the hose run for any signs of leaks. Look for wet patches or dripping fluid.
6. Consider a Separate Pump/Fuse: Consult your car's owner's manual or a workshop manual. Some vehicles have a dedicated pump for the rear washer or a separate fuse. This is a less common but possible scenario.

Preventative Maintenance for Your Washer System

Regular maintenance can prevent many of these issues from occurring in the first place:

• Use Quality Screenwash: Always use a good quality screenwash concentrate diluted with water (or a pre-mixed solution). This helps prevent freezing in winter, cleans better, and contains agents that discourage algae growth and limescale, which can clog jets. Never use just plain tap water.
• Keep the Reservoir Full: Check your washer fluid level regularly, especially before long journeys or during periods of bad weather.
• Clear Jets Regularly: Even if they're not blocked, a quick wipe over the jets when cleaning your car can help prevent build-up.
• Inspect Hoses: Periodically check the visible parts of the washer hoses for cracks or signs of wear.
• Winter Preparation: In colder months, ensure your screenwash has adequate antifreeze properties to prevent the fluid, pump, and lines from freezing and potentially bursting.

MOT Washer System Requirements Comparison

To provide a clear overview, here's a comparison table summarising the key differences in MOT requirements for front and rear washer systems:

Frequently Asked Questions About Car Washer Systems

Q: Will a non-working rear washer jet fail my MOT?

A: No, a non-working rear washer jet will not cause your car to fail its MOT, provided that your front windscreen washer system is fully functional and capable of clearing the front windscreen effectively. The MOT test specifically focuses on the driver's forward visibility.

Q: What if only one front washer jet works?

A: If only one front washer jet is working, your car will likely fail its MOT. The requirement is that the system must effectively clean the windscreen to provide the driver with a clear view. One jet often cannot achieve this across the entire required field of vision, especially if it's spraying weakly or in the wrong direction.

Q: Can I use plain tap water in my washer fluid reservoir?

A: It is highly recommended not to use plain tap water. Tap water can contain minerals and limescale that can clog the washer jets and the pump over time. In colder weather, plain water will freeze, potentially damaging the pump, hoses, and jets. Always use a proper screenwash concentrate diluted with water as per the manufacturer's instructions, or a pre-mixed screenwash solution, to ensure optimal performance and prevent damage.

Q: How often should I check my washer fluid level?

A: It's good practice to check your washer fluid level regularly, ideally once a week or every time you fill up with fuel. This is especially important during winter or periods of heavy rain and road spray when you'll be using the system more frequently. Don't wait until it runs out!

Q: What's the best type of screenwash to use?

A: The 'best' screenwash often depends on the season. In summer, a good quality screenwash that effectively removes insect splats and road grime is sufficient. For winter, it's crucial to use a screenwash with a strong antifreeze capability, typically rated for temperatures down to -10°C or -20°C, to prevent the system from freezing. Always check the product's specifications and dilute according to the manufacturer's instructions for the prevailing temperatures. High-quality screenwashes also often contain cleaning agents that prevent blockages and leave a streak-free finish.

Q: My washer pump sounds like it's working, but no fluid comes out. What's wrong?

A: If you can hear the pump whirring but no fluid is reaching the jets, the most common issues are either blocked jets or a leak in the washer fluid hose. Start by trying to clear the jets with a thin pin. If that doesn't work, inspect the entire length of the washer hose for any disconnections, cracks, or splits, as fluid could be leaking out before it reaches the nozzles.

Conclusion

To summarise, you can breathe a sigh of relief regarding your upcoming MOT. The good news is that your car will not fail its MOT due to a non-working rear washer jet, provided your front windscreen washer system is fully operational and effectively clears the windscreen. The MOT focuses on critical safety components, and while a working rear washer is convenient, it's not a mandatory safety item for the test. However, it's always advisable to get any non-functioning components repaired for your own driving comfort and the overall functionality of your vehicle. A proactive approach to vehicle maintenance ensures not only MOT success but also a safer and more pleasant driving experience.

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