QuestionI have a V reg VW Passat TDI Sport, it has done 104200 miles. When driving it seems to lack power initially and especially when Motorway driving. I can be doing 70 mph in a level section of Motorway but when I hit a hill the car slows to 60mph or less and the accelerator pedal is flat to the floor. Once over the hill it picks up speed again. I have had a diagnostic rum on it and the DTC error code is 17551, the VW error code is P1143. Can you advise on what is wrong please and what to do to cure the problem? Thanks.
AnswerIt is an error reading concerning air flow and air pressure's readings.
First of all I would check the air filter is not clogged, that would reduce the power and bring up this error code.
-- If the air filter appears clean then it could be a leak at the inlet manifold, you can have this tested at any garage for a modest sum.
If the intake manifold is not leaking AND the air filter is clean AND the problem still persists then it could be either the
-- MASS AIR FLOW SENSOR --
(this senses how much air is coming into the turbo if it reads low the amount of fuel delivered to the engine will be low, reducing power)
or the
-- INLET MANIFOLD PRESSURE SENSOR --
(this senses how much air - or rather the pressure of the air that actually goes into the engine if it reads low the amount of fuel delivered is reduced also)
Or
-- Leaking Vacuum Line from engine to turbo actuator --
(the vacuum from the engine tells the turbo to start working, if the line leaks you get no boost)
-- Worn turbo unit --
*when the turbo is worn or malfunctioning you get reduced boost or no boost)
Testing the manifold and replacing the air filter may cost £50 - but the price of the sensors.. about £150 each, Turbo £200 if your'e lucky for a reconditioned unit - so fingers crossed its a blocked air filter like I thought at first when I saw the question, or the vacuum line which is very cheap also.
Tell me how you get on, I like to know if I'm right or wrong...
