10 Apps To Aid You Manage Your Audi G28

How to Replace an audi key replacement key service (continue reading this) G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is located near the transmission's edge 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 within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends a signal to the G5 tachometer 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 reached TDC and also the position of the camshaft, to trigger the spark and injectors.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating 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).

It's a bit tricky to test since there are several connector pins, and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading approximately 1000 ohms. Examine for signs of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the fourth was unclean. When I crank the engine without sparks i put tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID but without success. The car will start if the G28 is not plugged in and runs fine when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not certain what to do, but i believe that i've eliminated everything else. But i'm worried that I may have missed something. If anyone has any ideas please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sensor is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. It is simple to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed of the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go bad you will get codes on the diagnostic scanner that could cause engine shut down.

The signs of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you have any of these issues it is likely that your sensor is going bad and should be replaced. The good news is they are quite affordable and easily accessible, especially when you're looking at an Bosch sensor, which is what we have. Alternately, the GM version of this part is also a good choice.

5. Tachometer

A faulty engine speed sensor could be the cause of numerous problems in your vehicle. It's a crucial component of the transmission of your audi spare key since it sends information to the ECU about how fast or slow the engine is spinning. When this sensor fails, it will cause problems for the transmission as well as the other car's components.

The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can 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 see around 1000 ohms of resistance between those two pins. This is a common component across the audi replacement keys 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.