20 Myths About Audi G28: Busted

How to Replace an audi key programmer G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky since there are two connector pins, and they have different functions however the best method of testing it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading about 1000 ohms. Look for signs of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday accelerating full speed from highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or the injectors aren't firing any more. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When I crank the engine, there are no sparks i put tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th one stays closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get 0ohm. I assume that the problem is in another location.

I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.

I'm audi key fob not working sure what to do. I feel like i've pretty much all other possibilities out. But i'm worried that I may have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. It is simple to test them to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft in order to make a decision about timing of the fuel injector, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

A damaged G28 sensor could cause an inaccurate gearbox speed counter or a gearbox that shifts more quickly than normal, or a misfire while in the gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these symptoms. The good news is that they are very affordable and readily available particularly in the case of a Bosch unit which is what we have. You can also choose the GM version of this part is also a good option.

5. Tachometer

A failing engine sensor could cause a variety of issues within your vehicle. It's an essential component of your Audi q3 key's transmission, because it communicates to the ECU about how the car's crankshaft is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.

The G5 engine speed sensor is situated 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 utilizes this signal to control the flow of fuel and boost and also timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can test the sensor replacement key for audi a4 failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between those two pins. This part is common across the audi replacement car keys 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU, so you might find good ones in wrecking yards.