The 12 Worst Types Of Tweets You Follow How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor serves as a reference for comparing with 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 start spark and injectors in the right way.

If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit tricky since there are two pins for the connector and they perform different functions however the best method to test it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should read approximately 1000 ohms. If you are having problems with this part, check for evidence of coolant or oil in the connector bay.


2. Injectors

Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, 3 were drenched with gazoline the fourth one was dry. I put tissue over each injector hole, and when i start the engine with no sparks, the 3 that have gazoline pop right out. audi replacement car keys shut. I tested the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. Therefore, i think the issue is somewhere else.

I also tried to reset PID without success. The car can start if the G28 is disconnected and it runs perfectly when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.

I'm not sure what to do, as i feel i have pretty much eliminated everything else. I'm afraid i may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is the same as the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. Testing them is easy by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

Some of the symptoms of a failed G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when you are in gear. If you are experiencing any of these issues, it is likely that your sensor is failing and should be replaced. They are cheap and easy-to-find, especially if they're a Bosch sensor like ours. Alternatively, the GM version of this unit is also a good option.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of numerous problems in your car. It is a crucial part of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is turning. When this sensor fails, it could cause problems for the transmission, as well as the other car's components.

The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to control the amount of fuel and boost, and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should observe approximately 1000 ohms resistance between those points. This part is common 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 may find some good ones in wrecking yards.