How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission, above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors according to the situation.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky since there are two pins for the connector and they serve different purposes however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when the sensor is operating at its maximum. If you are having problems with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss as if the engine was running out of gas or the injectors aren't firing anymore. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I placed a tissue over each injector hole, and when i start the engine with no sparks, the 3 with gazoline jump out. The 4th one remains shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. I assume that the problem is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However the intermittent misfire issue persists at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.
I'm not certain what to do, as i think i've pretty much completely ruled out all other possibilities. But i am afraid i might have missed something. If anyone has suggestions, please chime in! TIA!
3. audi a1 key Fuel Pump
The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or a parts store. Testing them is easy - put your DMM in resistance mode and measure between pins 1 (with the bump on audi tt keys the connector's end up) and 2 (2nd from left on the black end of the connector). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that needs to know the position and speed of the crankshaft in order to make decisions about timing of website the fuel injector, for example. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner get more info that can lead to engine shutdown.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal and/or misfiring when in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They're inexpensive and easy to locate especially if they're a Bosch sensor like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It's a vital component of your Audi's transmission, as audi key replacement it sends information to the ECU about how the car's crankshaft is spinning. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It transmits signals via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU, so you might find good ones in wrecking yards.