The Most Prevalent Issues In Audi G28

How to replace audi key fob an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located at the edge of transmission over the flywheel gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start 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 aren't in sync and could indicate the chain is stretched or a jump link on 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 as there are two different connector pins, and they perform different functions however the best method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. Look for evidence of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a significant reduction in power. It was like the engine was running out of gas. Or, my injectors weren't firing. This morning i pull out the spark plugs, 3 were drenched in gazoline, the 4th one was dry. When I start the engine without sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I think the issue is in another location.

I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do, but i think i've pretty much eliminated everything else. I'm concerned that i may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. It is simple to test them - 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 connector's side). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both 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 achieve this. If either of these goes badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.

A damaged G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. If you experience any of these problems, it is likely your sensor is deteriorating and needs replacing. They're cheap and easy to find especially in the case of an Bosch unit like ours. Alternately, GM's version this part is a good option.

5. Tachometer

A failing engine speed sensor could be a cause for numerous issues in your vehicle. It's a vital component of the new audi key's transmission since it relays information to the ECU about how the car's crankshaft is turning. If this sensor fails, it could cause problems for the transmission as well as the other car key replacement audi (mozillabd.science)'s components.

The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate the flow of fuel and boost as well as timig. It also relays it to the G5 Tachometer in instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between those points. This is a standard part across the audi a4 key replacement 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.