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Matt
Matt, Mechanical Engineer
Category: Car
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Experience:  BEng hons Mech engineering, in auto industry 22 years
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My wife has an Audi A3 1.6TDi 2010 Last February the car

Customer Question

My wife has an Audi A3 1.6TDi 2010
Last February the car started going into limp home and the coil indicator showed on the dash. After some head scratching we had the EGR Valve replaced and also had the car terracleaned which appeared to have solved the problem, until today !
The car has gone into limp home about 5 times today, an OBD scan shows an error of P0407$07E8 (Exhaust Gas Recirculation Sensor B Circuit Low)
Are there any other sensors/valve that could cause this error or have we got a dodgy EGR again ?
Submitted: 1 month ago.
Category: Car
Expert:  Matt replied 1 month ago.

Hello

an air / vacuum leak can sometimes also produce this fault
Normal
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MicrosoftInternetExplorer4

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

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if this checks out OK then yes I'd check over the connections to the EGR valve and the wiring loom

Expert:  Matt replied 29 days ago.

Hi

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