Why the Volkswagen Polo does not start
Volkswagen Polo 5 generation sedan body equipped with a 1.6 liter engine (1.6 MPI 105 hp) with automatic and manual transmission. The models with hatchback bodies were equipped with gasoline engines of 1.2 L (60 hp MPI, 70 hp MPI and 105 hp robotized transmission) and 1.4 L (85 hp MPI).
The power units of Volkswagen Polo cars operate steadily in harsh Russian operating conditions. After five to seven years of operation there may be problems with engine starting, especially in the cold season.
Possible signs of engine starting failure, causes of failure and sequence of troubleshooting
The main signs, causes and sequence of elimination of the problem of failure to start the engine Volkswagen Polo are shown in the table:
| Signs of engine start failure | Causes of malfunction | Repair sequence |
|---|---|---|
| The starter does not crank during engine starting. Lights on the dashboard go out during start | Typical faulty wiring and contacts of battery terminals. Possible loss of battery capacity after long parking, failure of one of the batteries. | Remove and clean battery terminals. Clean the wire connection from the battery negative terminal to the vehicle ground. Check the battery on the loading fork. Charge the battery. |
| The starter does not crank during startup, The lights on the instrument panel glow dimly. | Battery discharge after a long time of parking or in severe frost. | Warm the battery in a warm room. Recondition the battery. Replace the battery. |
| There is a clicking sound in the starter area when starting the engine, but the crankshaft will not turn | Insufficient battery charge. Burned pins of the starter retractor relay. Volkswagen Polo starter plug malfunction | Charge the battery. Check starter on the stand, if necessary make repair-restorative works. |
| Starter cranks, engine doesn’t start. | Engine control system malfunction, failure of fuses, relays serving the engine control unit, electrical wiring failure. Crankshaft, camshaft, air mass flow sensors failure. | Perform engine computer diagnostics, determine errors, decode, eliminate engine errors. Check fuses and relays. |
| Starter cranks, engine starts, runs irregularly, stops right away | Trouble in flow meter, crankshaft sensor, ignition system. Infringement of ignition angle of the engine. | Check ignition spark quality, spark plugs condition, ignition system. Perform computer diagnostics (check ignition angle). |
| The engine starts and immediately after a couple of seconds stalls | Breakdown of immobilizer communication, firmware, malfunction of the key chip, immobilizer pump loop, malfunction of the engine control unit power supply. | Check power and fuse circuits of the engine control unit. Try to start the engine with the second key. Perform computer diagnostics. |
| Engine stalls while driving, won’t start after that | Faulty petrol pump, fuse and relay of the petrol pump. Malfunction of electrical wiring | Check gas pump relay, fuse. Apply voltage directly to the gasoline pump (bypassing relay and fuse). Replace petrol pump if necessary. |
| No symptoms when ignition key is turned. | Faulty ignition switch contact group. | Repair ignition switch. |
Checking the fuses serving the engine control system
The experience of operating a Volkswagen Polo car shows that in many cases the engine start failure is associated with blown fuses or faulty relays. Therefore, troubleshooting should begin with their control. First of all, you should check the fuses, located in the underhood space.
It is necessary to check the fuse SA1 (responsible for charging the battery), SA3 (starter). Next, check the fuses, located in the cabin.
Fuses serving the engine control system have positions 3, 8, 10, 13, 17, 19, 23 and 36. If a fuse malfunctions, it must be replaced with a fuse of the same rating. It is not allowed to increase the fuse rating, let alone install a “bug” in its place. If a new fuse fails after installation, it is necessary to check wiring for short circuits.
In order to check the relay, you must remove the thruster panel, as shown in the figure:
Relay location and decoding.
Relays R3, R4, R5, R8 and R10 should be checked. Relay contacts layout is marked on its case.
Volkswagen Polo sedan does not start
Volkswagen Polo sedan. Starter cranks, but the engine does not start
The reasons for such behavior of the car can be quite a lot. The main ones are listed below
Human factor : You forgot to disable the anti-theft system, which blocks, for example, only the gasoline pump. The exhaust pipe is clogged. Kind people stuck a rag or a potato in it, or maybe you just drove into a snowdrift – there are many options. The exhaust pipe should be cleared out.
All of the above, in general, is not a breakdown, and is solved in two accounts. And now let’s analyze the reasons connected with technical malfunction: If the starter cranks quite slowly, the reason may be thickened in the cold oil in the engine. And it may be discharged after a long parking the battery or its heavily oxidized terminals. At the same time, the on-board voltage may drop so low that the engine control unit refuses to work. Well, everything is clear here: you should fill up the oil according to the season, charge the battery or replace it. Something is frozen – water in gasoline line, diesel fuel in tank or filter. Look for a warm box! The fuel pump is faulty. It’s easy to tell unless you’re trying to start the car near a busy and noisy highway. If it is quiet around, a sensitive ear can detect the absence of the fuel pump whirring sound during starter operation. At best poor contact in the circuit is to blame, at worst the pump will be replaced. The flywheel crown rotates. This sometimes happened on older cars, up to VAZ-2109. You can hear that the bendix has meshed with the crown, and the crown rotates on the flywheel with a squeal. The flywheel is about to be replaced.
The starter does not engage with the crown. Reason: Worn parts, chipped teeth, etc. Gearing grinding sounds when you try to start. Prepare to replace the crown or flywheel.
The bendix is stuck. Whether it’s the actuator or the bendix itself, it doesn’t matter. You can hear the starter motor spinning at high rpm, but there is no further attempt to crank the engine. Get ready to repair or replace the starter itself.
Failure of the ignition system in gasoline cars . Check everything in a row – plugs, coils, wiring, etc. Diesel car does not work glow plugs. The problem may be in the control unit, as well as in the power relay. The glow plugs themselves should also be checked – this will have to be dealt with.
The timing belt is blown to shreds . It’s easy to feel it: it’s easy for the starter to crank. If you are lucky (pistons did not meet the valves) – it is enough to replace belt, if not – half-motor.
Timing belt shifted a few teeth, having disturbed correct timing. Again, at best you need to return belt back to its place, but at worst expensive repair is waiting for you. Increased resistance to crankshaft rotation: scoring on shafts, bearing shells, cylinder-piston parts, deformation of shafts. Check whether the engine can be cranked when pushing the car with a manual gearbox in top gear. With an automatic, you will have to try to crank the engine by the auxiliary drive pulley bolt. If the engine can be cranked relatively easily, you will have to continue searching for the cause.
Stuck alternator, power steering pump, air conditioner compressor. Faulty unit doesn’t let the engine rotate. To check it, you can first see if the belt is not straining too much when trying to crank the engine. If suspicions are confirmed, it is possible to remove auxiliary drive belt and try to drive to a service station on your own. Of course, this will only work on cars where the coolant pump rotates the timing belt. With a non-functioning pump, without coolant circulation, even a cold engine will quickly boil over. At night, your car was attempted to be stolen, but something went wrong. As a result, the intruders rummaged around, broke something and disappeared in disgrace. Without diagnostics at service station the problem will not be solved.
If the starter cranks, but the engine doesn’t start, first of all you should check the power system and ignition system. Please note that all these checks should be performed only when the starter cranks smoothly, without jerks. Otherwise (jerks when the starter works or clicks instead of the usual buzzing) the problem should be looked for in the starter first of all.
Check the fuel system should be performed sequentially – from the fuel pump to the injector (carburetor):
1. If you have an injector, when you turn on the ignition you should hear the whirring of the electric gas pump in the cabin. If there is no buzzing, it means either the gasoline pump motor is burnt out or there is no voltage on it. Consequently, check the fuel pump and its fuse.
2. With carbureted cars everything is a bit more complicated: gasoline pump is driven by camshaft, so to check it you have to take the end of hose from carburetor inlet connection or gasoline pump outlet connection. If you swing the gasoline pump manual pump lever several times, gasoline should come out of the connection or hose.
3. To check the presence of gasoline in the injector ramp, press the valve on the pump connector: gasoline should flow from there.
4. be sure to check if the fuel filter is clogged. The engine probably just doesn’t have enough fuel, so it won’t start.
5. 5. Another reason why the starter cranks but the car won’t start is a clogged throttle valve.
After performing all the above steps, you can try to start the car again. If the starter still cranks, but the car does not start, then you need to move on to checking the ignition system.
1. First you should unscrew the spark plug and check the presence of spark on it. To do this, you need to put the high-voltage wire on the plug, touch the skirt of the plug to the metal part of the engine and crank the engine with the starter (you need an assistant for this). If there is a spark, then the spark plug is good.
2. If there is no spark in the injector car, then the problem is in the ignition module.
3. If there is no spark in the carburetor engine, then the ignition coil should be checked. Take the central wire out of the trambler cover, place its end 5 mm from the metal part of the engine (without touching it) and ask an assistant to crank the engine with the starter. If there is no spark, the coil is defective.
4. If there is a spark and the ignition coil is good, you should remove the trambler cap and see if there are any defects under it (soot, cracks, etc.).
There are cases when all these checks are not enough, and the car owner has to do more in-depth checks to find the cause of the starter, but the engine does not start. Among the reasons why this may be the case, there are also:
1. A blown fuse. This is not common, but it is still worth checking the integrity of the fuses in the units.
2. Corrosion on any of the electrical parts.
3. Condensation under the hood. There were cases when the car didn’t start just because of excessive moisture under the hood.
