How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging as there are two different connector pins, and they perform different functions but the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading around 1000 ohms. If you're experiencing issues with this sensor, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs, 3 were drenched with gazoline the 4th one was dry. I put tissue over each injector hole, and when i start the engine without sparks, the ones that have gazoline pop right out. The fourth one remains shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is elsewhere.
I also tried to reset PID but without success. The car will start when the G28 is not plugged in and it runs perfectly when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, as i believe that i've eliminated everything else. I'm afraid i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. Test them out by putting your DMM in resistance mode and check here measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft to make decisions regarding timing of fuel injectors, etc. In order to do this it uses a click here Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.
A failing G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, and/or a misfire while in gear. It is probable that the sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find particularly in the case of a Bosch unit like ours. Alternately, GM's version this part is an option.
5. Tachometer
A malfunctioning engine sensor can get more info cause a number of problems in your vehicle. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU on how fast or slow the car's engine is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine read more sensor is located at the edge of the transmission, over the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer located in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms in these areas. This is a common feature across the Audi 80-100-200-RS2 model, replacement key for audi a3 ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du So, you may find some good ones in wrecking yards.