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How to Replace an Audi replacement key service G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission, above the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on 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 an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

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

If this sensor fails, the ECU will throw the P00160 error, 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 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 connector pins, and they have different functions however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is in full operation. Examine for signs of coolant, or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive drop in power. It was like the engine was running out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, three were drenched with gazoline the fourth was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stay shut. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero Ohm. I think the issue is elsewhere.

I also tried to reset PID but without success. The car is able to start when the G28 is disconnected and runs fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do, but i believe that i've ruled out everything else. However, i'm afraid that I may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. It is simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, for example. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

Some of the symptoms of a failing G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when you are in gear. If you have any of these issues it is likely your sensor is deteriorating and requires replacement. They're cheap and easy to find, especially in the case of a Bosch unit like ours. Alternately, GM's version this component is an option.

5. Tachometer

A damaged engine sensor could cause a myriad of issues within your vehicle. It's an essential component of your audi a3 keys's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. If this sensor fails, it will affect the performance of the transmission as well as the other car's components.

The G5 engine speed sensor is situated on the edge cost of audi key replacement the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and processes this signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from 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 and pin T26a/12. You should see approximately 1000 ohms resistance between those two pins. This is a standard part that is found across the audi key blade 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.