5 Laws That Anyone Working In Audi G28 Should Be Aware Of

How to Replace an audi connect key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, replacement audi A3 key then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via an uncolored wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used as a reference replacement key for audi comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors according to the situation.

If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. However the code will not appear on its own, without additional information from other sensors (G4 and G40).

Testing can be a bit difficult as there are two different connector pins and they have different functions but the most effective method to test it is by measuring resistance between the sensor and the ECU. When the sensor is fully functional, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant drop in power. It was like the engine had run out of gas. Or, my injectors weren't firing. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth was dry. I put tissue over each injector hole, and when i start the engine with no sparks, the ones with gazoline jump out. The 4th one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero ohm. I assume that the problem is elsewhere.

I also tried to reset PID without success. The car will start when the G28 is disconnected and runs fine when it is connected however it 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 bar while the actual pressure is zero.

I'm not certain what to do, as i feel i have pretty much ruled out everything else. I'm afraid i may have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal 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 wrecking yard or from 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 of our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger the engine shutting down.

Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal and/or misfiring when in gear. It is possible that the sensor is failing and requires to be replaced if you experience any of these symptoms. The good news is they are quite affordable and easy to find, especially if you're looking at the Bosch unit like ours. Alternatively, the GM version of this unit is also a good option.

5. Tachometer

A malfunctioning engine speed sensor could be the reason behind a slew of problems in your car. It is an important part of the transmission in your audi key replacement Cost because it relays information to the ECU on how fast or slow the engine of the car is spinning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine speed sensor is located at the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then processes the signal to control the flow of fuel, timig and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking 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 [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe around 1000 ohms of resistance between those points. This is a common feature across the audi key programming 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 may find good ones in wrecking yards.