How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors in the right way.
If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It can be a bit difficult to test since there are several pins on the connector, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should be reading around 1000 ohms. If you're having issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were drenched with gazoline the fourth was dry. I put tissue over each hole in the injector and when I start the engine with no sparks, the 3 with gazoline jump right out. The fourth one remains shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I assume that the problem is somewhere else.
I also tried to reset the PID but without success. The car can start if the G28 is disconnected and is running fine when it is connected however it has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not sure what to do, as i think i've pretty much ruled out everything else. However, i'm afraid that I might have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. Test them out - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector 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 has to be aware of the speed and position of the crankshaft to make a decision about fuel injector timing etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will show the codes that could trigger an engine shut down.
A malfunctioning G28 sensor could result in an inaccurate speed counter for lost audi key the gearbox, a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you experience any of these issues it is most likely that your sensor is failing and needs replacing. They are cheap and easy-to-find, especially in the case of a Bosch sensor like ours. Alternatively, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind many issues in your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU regarding how fast or slowly the engine of the car is turning. This sensor can cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear and transmits get more info a signal to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to regulate the flow of fuel and boost and also timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin website T6a/1 (trace read more [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a standard component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good parts could website be found in wrecking yards.