This Is The Ugly Truth About Audi G28

How to Replace an audi key 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, above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer 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 signals to ECU pin T55/49 via a grey wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indication 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 has to know when the crankshaft has reached TDC, and the location of the camshaft in order to activate the spark and injectors.

If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).

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

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a significant drop in power. It was like the engine was running out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs, programming audi key spare audi key programming cost (https://instapages.stream/story.php?title=seven-reasons-why-audi-a3-replacement-key-is-so-important) three were soaked with gazoline and the fourth was dry. I put a piece of tissue over each hole in the injector and when i start the engine without sparks, the 3 that have gazoline pop right out. The fourth one remains shut. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero ohm. I assume that the problem is elsewhere.

I also tried to reset PID without success. The car can start if the G28 is not plugged in and is running fine when it is connected however it is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug 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. I think I've eliminated everything else. But i'm worried that i might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to 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 by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's end). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines needs to be aware of the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes bad you will get codes on the diagnostic scanner which can lead to engine shutdown.

A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or an unfire when in gear. It is probable that the sensor is failing and requires to be replaced if you notice any of these signs. They are cheap and easy-to-find especially when they're a Bosch model like ours. Alternatively, GM's version of this part would be an option.

5. Tachometer

A damaged engine sensor could cause a variety of issues within your vehicle. It's a vital component of your audi key replacement's transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those two pins. This is a standard component across the audi key blade 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.