Many Of The Most Exciting Things That Are Happening With Audi G28

How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge, above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer on 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 signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.

If this sensor fails, the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test because there are several pins on the connector, and each one has different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. If the sensor is functional, it should read about 1000 ohms. If you are having problems with this part, check for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. When i crank the engine without sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th stay shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming that the issue is somewhere else.

I also tried to reset PID without success. The car can start when the G28 is disconnected and is running fine when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I think I've eliminated everything else. However, i'm afraid that i might have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and they both work in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is simple to test them: simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make decisions about timing of the fuel injector, for example. To accomplish this, it makes use of a Crank Position Sensor (G4) and an website Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

A damaged G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, and/or an unfire when in gear. If you are experiencing any of these issues, it is likely that your sensor is deteriorating and needs replacing. They're inexpensive lost audi key and easy to locate particularly in the case of a Bosch model like ours. Alternately, check here GM's version this part is an excellent choice.

5. Tachometer

A failing engine sensor could cause a number of problems within your vehicle. It is an important part of the transmission in your Audi because it relays information to the ECU about how fast or slowly the car's engine is spinning. This sensor could cause the transmission to malfunction and other components of the car to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, and more info also to timigrate. It also sends it 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 here (trace [79]), and between pin T6a/1 and pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du You may also find them in wrecking yards.