What is the fault when the Transit SVS light is on and how to solve it?
5 Answers
The Transit SVS light may come on due to the following reasons: 1. Poor fuel quality: Many car owners who notice the engine fault light on have experienced that the light suddenly comes on after refueling with a certain batch of gasoline. This is because the engine has specific requirements for fuel quality indicators, especially as regulations worldwide increasingly demand higher standards for engines, thus raising the bar for fuel quality. Poor fuel quality can also trigger the light. In this case, it is necessary to replace the fuel. 2. Dirty engine cylinders or carbon buildup: Over time, carbon deposits inevitably accumulate inside the engine. These deposits can alter the engine's designed parameters and, due to their unstable nature and heat retention, can cause irregular ignition, leading to engine knocking. Under such circumstances, the engine fault light will come on. In this case, the inside of the cylinders needs to be cleaned.
I've fixed quite a few Transit's SVS light issues, and when this thing lights up, it's mostly the engine system acting up. The most common issue is errors from the after-treatment system, like a clogged particulate filter, a stuck urea nozzle, or a faulty exhaust temperature sensor triggering it. Last time, an owner used poor-quality diesel from a small gas station, which directly caused the DPF to clog and trigger an alarm. I recommend first using a diagnostic tool to read the fault codes—don't just guess and fix blindly. Electrical issues are also common, like loose connectors or worn-out wiring harnesses. Clean what needs cleaning and replace what needs replacing. After the repair, remember to run a 20-minute regeneration cycle. If you really can't figure it out, go to a 4S shop—never randomly pull fuses on your own.
Our fleet's old Transit often has the SVS light on, and after some troubleshooting, we found out it's because the urea nozzle was clogged with crystallization. Actually, this light is like the vehicle crying out in pain, usually indicating an issue with the exhaust treatment system. You need to check three areas: the urea system (including fluid level and nozzle), DPF status, and various exhaust sensors. If you're doing it yourself, first turn off the engine, wait five minutes, and restart—some false faults might disappear. If the light stays on, you'll need to scan for trouble codes; codes starting with P are mostly engine-related issues. Be careful with the injection lines during repairs—they're highly corrosive. Regularly use qualified urea fluid and take the vehicle for a half-hour high-speed run to help with DPF regeneration.
Don't panic when the SVS light comes on—it's just your vehicle's self-check system alerting you. For the Ford Transit, common triggers fall into three categories: abnormal urea fluid concentration (check for crystallization in the urea tank), excessive exhaust backpressure (indicating DPF clogging, requiring professional regeneration), and electrical faults (often caused by water ingress or oxidation in sensor connectors). The key is to use the OBD port to read precise fault codes—don't replace parts blindly. Occasional faults might disappear after a restart, but frequent illumination demands inspection. Once, my oxygen sensor wiring got melted by the exhaust pipe—reconnecting it solved the issue. After repairs, always clear the fault codes and road-test for verification.
When driving a Transit for deliveries, the most dreaded scenario is the SVS light coming on, which indicates excessive emissions or powertrain abnormalities. The actual response should be prioritized based on severity: if flashing, limit speed and head to the workshop immediately; if steady, it can be delayed but don't procrastinate. Start with the basics—first check if the urea fluid is depleted or of poor quality, then inspect the air flow sensor for dirt. If the regeneration button doesn't work, it means the DPF is severely clogged and requires specialized equipment to fix. Poor fuel quality can trigger false NOx sensor alerts; try switching to two tanks of standard diesel. For electrical checks, measure circuit voltage—overheated relays indicate a short. Repair costs can range from hundreds to thousands, so early intervention saves the most money.
