7 Little Changes That Will Make The Difference With Your Audi G28 How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49), then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors in the right way.

If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).

It's a bit tricky to test as there are several connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is operating at its maximum. Look for signs of coolant, or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced massive power loss like the engine is out of gas or the injectors are not firing anymore. I pulled out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. I put tissue over each injector hole and when I start the engine without sparks, the three with gazoline jump out. 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'm assuming that the issue is elsewhere.

I also tried to reset the PID without success. The car is able to start if the G28 is unplugged and runs fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I'm not sure what to do. I believe that I've all other possibilities out. However, i'm afraid that I may have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will show codes that could lead to an engine shut down.

The signs of a failing G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when you're in gear. If you are experiencing any of these issues it is most likely that your sensor is going bad and should be replaced. They're cheap and easy to find, especially if they're an Bosch sensor like ours. You can also choose the GM version of this part is also a good choice.

5. Tachometer


A damaged engine sensor could cause a myriad of issues in your vehicle. It's a crucial component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine of the car is turning. When this sensor fails, it will disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost and also timig. It also relays 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 to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. replacement audi key thekeylab.co.uk should see approximately 1000 ohms of resistance between those two pins. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du You may also find some good ones in wrecking yards.